Updated API endpoint (SharePoint#2530)

Updated the `RemoveTenantTheme` API endpoint to `DeleteTenantTheme`. The `RemoveTenantTheme` doesn't exist, so the `DeleteTenantTheme` is the correct one to call.

Author: estruyf

docs/declarative-customization/site-theming/sharepoint-site-theming-rest-api.md

@@ -22,13 +22,13 @@ Before you get started, make sure that you're familiar with the following:
 The following REST commands are available for working with site themes:
 
 * __AddTenantTheme__ – create a new theme; similar to the Add-SPOTheme SharePoint cmdlet
-* __RemoveTenantTheme__ – remove a theme from the tenant store; similar to the Remove-SPOTheme PowerShell cmdlet
+* __DeleteTenantTheme__ – remove a theme from the tenant store; similar to the Remove-SPOTheme PowerShell cmdlet
 * __GetTenantThemingOptions__ – read theme settings
 
 The URL for theme management REST commands is based on _api/thememanager. For example, the following are the endpoints for the commands:
 
 * `http://<site url>/_api/thememanager/AddTenantTheme`
-* `http://<site url>/_api/thememanager/RemoveTenantTheme`
+* `http://<site url>/_api/thememanager/DeleteTenantTheme`
 * `http://<site url>/_api/thememanager/GetTenantThemingOptions`
 
 ## AddTenantTheme
@@ -87,7 +87,7 @@ RestRequest("/_api/thememanager/AddTenantTheme", {name:"Sounders Rave Green", th
 
 <br/>
 
-## RemoveTenantTheme
+## DeleteTenantTheme
 
 The following JavaScript sample code shows how to remove a theme.