diff --git a/spec/integ/matrix-client-methods.spec.ts b/spec/integ/matrix-client-methods.spec.ts
index a665aef86..21d224150 100644
--- a/spec/integ/matrix-client-methods.spec.ts
+++ b/spec/integ/matrix-client-methods.spec.ts
@@ -1336,18 +1336,25 @@ describe("MatrixClient", function () {
         it.each([
             {
                 userId: "alice@localhost",
+                powerLevel: 100,
                 expectation: {
                     "alice@localhost": 100,
                 },
             },
             {
                 userId: ["alice@localhost", "bob@localhost"],
+                powerLevel: 100,
                 expectation: {
                     "alice@localhost": 100,
                     "bob@localhost": 100,
                 },
             },
-        ])("should modify power levels of $userId correctly", async ({ userId, expectation }) => {
+            {
+                userId: "alice@localhost",
+                powerLevel: undefined,
+                expectation: {},
+            },
+        ])("should modify power levels of $userId correctly", async ({ userId, powerLevel, expectation }) => {
             const event = {
                 getType: () => "m.room.power_levels",
                 getContent: () => ({
@@ -1364,7 +1371,7 @@ describe("MatrixClient", function () {
                 })
                 .respond(200, {});
 
-            const prom = client!.setPowerLevel("!room_id:server", userId, 100, event);
+            const prom = client!.setPowerLevel("!room_id:server", userId, powerLevel, event);
             await httpBackend!.flushAllExpected();
             await prom;
         });
diff --git a/src/@types/IIdentityServerProvider.ts b/src/@types/IIdentityServerProvider.ts
index 05793d53a..8e3049740 100644
--- a/src/@types/IIdentityServerProvider.ts
+++ b/src/@types/IIdentityServerProvider.ts
@@ -20,5 +20,5 @@ export interface IIdentityServerProvider {
      * for the associated client.
      * @returns Promise which resolves to the access token.
      */
-    getAccessToken(): Promise<string>;
+    getAccessToken(): Promise<string | null>;
 }
diff --git a/src/client.ts b/src/client.ts
index 5ea515fe9..d46116675 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -4130,7 +4130,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
     public setPowerLevel(
         roomId: string,
         userId: string | string[],
-        powerLevel: number,
+        powerLevel: number | undefined,
         event: MatrixEvent | null,
     ): Promise<ISendEventResponse> {
         let content = {
@@ -4141,13 +4141,16 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
             // existing client state with a failed power level change
             content = utils.deepCopy(event.getContent());
         }
-        if (Array.isArray(userId)) {
-            for (const user of userId) {
+
+        const users = Array.isArray(userId) ? userId : [userId];
+        for (const user of users) {
+            if (powerLevel == null) {
+                delete content.users[user];
+            } else {
                 content.users[user] = powerLevel;
             }
-        } else {
-            content.users[userId] = powerLevel;
         }
+
         const path = utils.encodeUri("/rooms/$roomId/state/m.room.power_levels", {
             $roomId: roomId,
         });
@@ -8746,18 +8749,19 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
         email: string,
         clientSecret: string,
         sendAttempt: number,
-        nextLink: string,
+        nextLink?: string,
         identityAccessToken?: string,
-    ): Promise<any> {
-        // TODO: Types
-        const params = {
+    ): Promise<IRequestTokenResponse> {
+        const params: Record<string, string> = {
             client_secret: clientSecret,
             email: email,
             send_attempt: sendAttempt?.toString(),
-            next_link: nextLink,
         };
+        if (nextLink) {
+            params.next_link = nextLink;
+        }
 
-        return this.http.idServerRequest(
+        return this.http.idServerRequest<IRequestTokenResponse>(
             Method.Post,
             "/validate/email/requestToken",
             params,
@@ -8788,7 +8792,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
      * @param identityAccessToken - The `access_token` field of the Identity
      * Server `/account/register` response (see {@link registerWithIdentityServer}).
      *
-     * @returns Promise which resolves: TODO
+     * @returns Promise which resolves to an object with a sid string
      * @returns Rejects: with an error response.
      * @throws Error if no identity server is set
      */
@@ -8797,19 +8801,20 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
         phoneNumber: string,
         clientSecret: string,
         sendAttempt: number,
-        nextLink: string,
+        nextLink?: string,
         identityAccessToken?: string,
-    ): Promise<any> {
-        // TODO: Types
-        const params = {
+    ): Promise<IRequestMsisdnTokenResponse> {
+        const params: Record<string, string> = {
             client_secret: clientSecret,
             country: phoneCountry,
             phone_number: phoneNumber,
             send_attempt: sendAttempt?.toString(),
-            next_link: nextLink,
         };
+        if (nextLink) {
+            params.next_link = nextLink;
+        }
 
-        return this.http.idServerRequest(
+        return this.http.idServerRequest<IRequestMsisdnTokenResponse>(
             Method.Post,
             "/validate/msisdn/requestToken",
             params,
diff --git a/src/http-api/fetch.ts b/src/http-api/fetch.ts
index 1267fcc76..ecb09084b 100644
--- a/src/http-api/fetch.ts
+++ b/src/http-api/fetch.ts
@@ -70,7 +70,7 @@ export class FetchHttpApi<O extends IHttpOpts> {
         this.opts.idBaseUrl = url;
     }
 
-    public idServerRequest<T extends Record<string, unknown>>(
+    public idServerRequest<T extends {} = Record<string, unknown>>(
         method: Method,
         path: string,
         params: Record<string, string | string[]> | undefined,