Deborah, Miruna's solution didn't work for you not because of the double slash, but because of the (\d+). On the other hand, Derek's solution worked for you because of the (\S+). abc\W(\S+) might work here, but it will also "work" on something like
Or any string where the fourth character is something other than a letter or a digit, since that's what \W means. This might be what you want, but from your original description, it likely is not.
As for the part following that, (\d+) doesn't work because the slash is followed by AA, which is not matched by \d+ since \d only matches digits (it would, however, work on an input like abc\123456). In the suggested solution, (\S+) worked because that matches "anything other than a space character". That means the suggested solution would also match abc\#$%^& by trimming the abc\. This might be what you want, but it might also not.
From your description, the regex you'd most likely want would be
or maybe even
(everything after the abc\, including spaces, endlines, and other words, in the case the input you are trimming from is the entirety of the input you want)
This is all depending on how restrictive you want the capture to be.