Is it possible to remove a command completion from the "right arrow" completions?

[pfmoore]

When I type part of a command, PSReadLine displays a suggested completion after the cursor, and pressing the right arrow key will complete the rest of that suggested command.

At some point, long in the past, I appear to have accidentally typed the command "exit#", and now, whenever I type "exit", I see that gost "#" displayed as a potential completion. It's not exactly a disaster, but it's annoying and I'd like to get rid of it. Is there any way to do so? Presumably the list of potential completions is stored somewhere, and hopefully there's a way of managing it? I'd rather not clear everything - most of the time, the completions I see are useful and I'd hate to start building up a good set from scratch again - but if I could selectively remove unwanted items, that would be ideal.