Use the SFTP Remove Files action to delete a multiple files from the SFTP server. To delete a single file it's easier to use SFTP Remove Directory action.
Enter the path on the remote server. Make sure the full path is included (specified from the user's home directory) as the SFTP protocol doesn't have the concept of a "current directory" like FTP does.
Enter the remote mask to match against the files and directories to delete. Case Sensitive specifies whether to treat filenames case-sensitively.
Specify the recursive option to delete files in child directories also.