no...Backspace or Delete keys don't do it...
I tried editing the com.apple.screensharing.plist preference file and manually removed the computers, which seemed to reset my Screen Sharing tweaks (which were done using the terminal commands suggested by MacWorld
here, but then when I re-entered the terminal commands in the aforementioned article to restore my tweaks, I noticed that doing so also removed the various items listed in the "My Computers" section of the screenshot above, which was my main objective to begin with...
Probably not the cleanest way to do it, but it worked