To suspend or unsuspend a user, access to Supply Chain Administrator is required (usually located on the server) and the 'SA' credentials to be able to log into it.
Log into Supply Chain Administrator using SA or equivalent credentials.
In the top ribbon, click Users. A list of users will appear.
Find the user name to be changed and highlight it.
Right-click and select Suspend User. This will suspend them if they are not suspended or unsuspend them if they currently are suspended.
Check the user either has access or not as required to the Supply Chain application.