as to search:

the key to success here is choosing the right keywords/ search terms

for your problem:
click “search” above, and enter
Norton uninstal
into the search field

this gives some hits, where you should find some general strong advice on your NORTON/avast issue & hints on how to properly and completely remove NORTON
(which can be done after downloading avast, but MUST be done pior to installing avast or any other AV)

P.S.: BEFORE you uninstall Norton, make sure that you have ALL Windowsupdates applied…!!