If you want to remove/delete a computer from your Splashtop account, there are several ways:
Option 1: Uninstall the Splashtop streamer on the computer.
How to uninstall Splashtop? – Splashtop Business - Support
Option 2: log in at my.splashtop.com, find the computer in your list, click on the three dots icon for more options and choose "Delete computer"
A popup window opens ask you to confirm you want to delete that computer.
Option 3: Use bulk actions to remove multiple computers at time in All Computers list. This option is only available for team owner and admins. (Management > All Computers) Then go to Actions on top and choose delete computers.
A popup window will open and ask you to confirm you want to delete these computers.
Last Online filter
On the Management--All Computers screen, you can click the filter button to filter down the list of computers by the last online time. The available options are: All time, more than 90, 30, and 7 days ago or you can adjust the range yourself.
Option 4: On the Windows or Mac application, click on the gear icon next to the computer,
then click on the delete computer button from the bottom of the window.