When your Terminal server has many users and they use different printers.

You should install those printers on the TS first and then user can map it to their local printers.

One user, one printer will need a session on the TS.

When user log off, sometimes the printer sessions can't be log off automatically. A long time ago, many sessions will make users confuse.

So we need to delete them.

If you delete them in printer management, sometimes, it will fail.

So you can delete them in regedit: My computer\hkey_local_machine\software\microsoft\windowsNT\currentversion\print\printers

Just delete printers which they have a session. Them you need to logoff and then login again, those printers will disappeared.