Hello there, I’m B and I’m new, here. 
I tried searching but unfortunately, I haven’t found anyhing… 
I edited a mp3 file, trying to add the “stuio fade out” ath the end but, as the title says, as the track ends, I hear a sound, similar to the one you can hear when you pull out a jack… And the issue is that I can’t remove it. Can anyone help me, please? Thanks in advance.
Try Edit > Undo “Studio Fade Out” then Effect > Normalize with only “Remove DC offset…” checked, then Effect > Studio Fade Out" again.
See here for explanation: http://manual.audacityteam.org/o/man/faq_editing.html#clicks .
Gale