Need to replace part of uri in url. Tried many irules

ok, so iRule 1, you say string to lower and then check against a string with captitals, that won't work. either remove the string to lower (wouldnt do that) or replace the string without capitals "/sites/mkt/cpteam/"

iRule 2 seems to do what you want, i would add some logging to show that. if it then "doesn't work" then it might be an error in what you replace or the application not handling the rewriting well. you need to provide more info to look into that

iRule 3 and 4 use a redirect that usually is a different approach then rewriting and might open all kind of other issues.

by now i have another question, why are you doing this? isn't it easier just to use how it should be, rewriting adds complexity you want to prevent if not really needed.