Deleting a user permanently removes the user from the system. The user can no longer access the App Catalog or the Admin Portal. If a deleted user tries to log in, the user will see a message that advises the user to contact support.
If you may need to grant access to the user again in the future, you should disable instead of delete the user. For instructions, see Disable or Enable a User.
A deleted user will be blocked from running apps with any of these policies applied: Enterprise SSO, App Usage, Collect Crash Reports, Self Updating App, Runtime Integrity, or Data Wipe. For more information on applying policies, see Apply Policies to an App.