You can delete a connection by using the Delete action. 

NOTE: You need to have View/Read/Write/Manage iModelHub permission defined in Role Based Access Control.

Delete a connection and associated changes

At the moment, you can make these edits to an iModel when deleting a connection:

1. Delete a connection but keep already synchronized changes. This will stop future file synchronization, but will not delete the existing changes from an iModel.
2. Delete a connection along with synchronized changes from an iModel. This will stop future synchronization and will delete those files' data from an iModel. 

Files from deleted connections can be synchronized with other connections.