Q: how can I remove a computer from my time capsule?  do I need to reset it?  what if there are other computers backed up on it?

Not sure exactly what you are asking.  Are you saying that you want to stop a Mac from backing up to the Time Capsule?  Or, do you no longer have a specific Mac and you want to remove only the backups of that Mac from the Time Capsule without affecting backups of other Macs.....Or....something else?

On the Mac that you normally use to administer the network......

Click on the smiley face Finder icon at the bottom of the screen on the dock

In the Finder window that appears, look for the Time Capsule icon under the Shared heading on the left side panel of the window. In the example below, my Time Capsule is named TC

Click on the Time Capsule icon

That will display a folder in the window to the right named "Data" (unless you have changed the name of the Time Capsule hard drive)

Double click on "Data' to open the drive (if you have not done this before, you will likely be asked for the Time Capsule admin password)

In the next window that appears you will see a sparsebundle file for each of the Macs that have backups on the drive

Be very careful to select the sparsebundle file with the name of the Mac whose backups you want to delete by clicking on the file to highlight it

Click the gear icon above the window and select Move to Trash

Check again to make sure that you are deleting the file that you want.....there is no going back once you click to confirm

Click to confirm that you want to delete the file.

It may take a few minutes for the file deletion to complete, depending on how much data there is in the file to delete.