On the Admin service page, there are a few options you can perform.
Suspend
This option will suspend all domain(s) under this hosting package.
Special Note
Once the domain is suspended, the domain will no longer resolve the DNS queries, Email forwarding, etc...
Unsuspend
This option will resume all domain(s) under this hosting package.
Terminate
This option will remove all domain(s) under this hosting package from your WHMCS system and DirectAdmin servers.
Migrate
This option will allow you to migrate all domain(s) under this hosting package onto another DirectAdmin server.