I find the easyest way is to transfer it to epub with calibre then edit it with Sigil to remove the Generated by ABC Amber LIT Converter,
http://www.processtext.com/abclit.html
Once you open it in Sigel copy & paste Generated by ABC Amber LIT Converter,
http://www.processtext.com/abclit.html into the find spot then hit delete twice.
It is a pain to do but it is the only way i no of to get rid of it. then save it & reoplen in calibre & convert it back to pdf if that's the format that you want.
You can also fix or make chapters in sigil bc I like having it chaptered.