What would that be?
As Convert>Tag-Tag has a preview, you should see the immediate result, here: the string without that part in the brackets.
Also, as you can see the input field in the dialogue is labelled "Format string".
You copy and paste the string that I suggested into that field.
Now, a regular expression leads to no result (here: the string stays as it is) if the pattern does not match. So instead of giving
it would be better so see a real life string.
To see more about regular expressions, see the help:
https://help.mp3tag.de/options_format.html#regexp
There is, of course, the way to replace a string constant with nothing, e.g. with an action of the type "Replace" for TITLE
Search string: (revised by Salieri)
Replace string:
(leave empty)
This works only for this exact string. if you have versions with "(revised by Clementi)" then it would not work - the regular expression would cater for both cases.