This document explains how to delete Single Message Transforms (SMTs) from an existing Pub/Sub topic.
To delete topic SMTs, you can use the Google Cloud console, the Google Cloud CLI, the client library, or the Pub/Sub API.
Required roles and permissions
To get the permissions that
      you need to delete topic SMTs,
    
      ask your administrator to grant you the Pub/Sub Editor 
( roles/pubsub.editor 
)
     IAM role on your project.
  
  
  
  
  For more information about granting roles, see Manage access to projects, folders, and organizations 
.
This predefined role contains the permissions required to delete topic SMTs. To see the exact permissions that are required, expand the Required permissionssection:
Required permissions
The following permissions are required to delete topic SMTs:
- Grant the update a topic permission on the topic: projects.topics.patch
- Grant the view a topic permission on the project. This permission is only required if you are using the Google Cloud console: pubsub.topics.view
You might also be able to get these permissions with custom roles or other predefined roles .
You can configure access control at the project level and at the individual resource level.
Delete topic SMTs
To delete topic SMTs, follow these steps:
Console
-  In the Google Cloud console, go to the Pub/Sub Topicspage. 
-  Click the topic for which you want to delete an SMT. 
-  In the topic details page, click Edit . The Transforms tab lists all the SMTs that are attached to the topic. 
-  Click the delete button for the SMT you would like to delete. 
-  Click Update . 
gcloud
-  In the Google Cloud console, activate Cloud Shell. At the bottom of the Google Cloud console, a Cloud Shell session starts and displays a command-line prompt. Cloud Shell is a shell environment with the Google Cloud CLI already installed and with values already set for your current project. It can take a few seconds for the session to initialize. 
-  This command deletes all SMTs associated with the specified topic. Run the gcloud pubsub topics updatecommand with the--clear-message-transformsflag:gcloud pubsub topics update TOPIC_ID --clear-message-transforms Replace the following: -  TOPIC_ID : The ID or name of the topic you want to update. 
 To instead remove a single SMT, refer to Update topic SMTs and create a new message-transforms-filethat excludes the SMT you wish to delete.
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