How to remove the footer link on invoices?

The 5th post in that thread Remove Link Up of printed voucher and report - #5 by Mohamed_Mamdouh explains it simply also.

There are plenty such as:

etc.

Obviously when none of these suggestions are working then you are still advised to explore the forum further.

Also the recent "Start PM with an AI Chatbot "(robot-head next to search-magnifier) would have provided you with a more extensive list. If you enter the title of this topic then it shows that this thread already exists and includes a solution. However, when you change it a bit to for example “unnecessary links in footer” you would see your topic and several others popping up.

That users do not mark an item resolved when they are is indeed not desirable but most solutions unfortunately do not get marked by the originators of the posts that explained the issues.