Should I erase Website data in settings? I'm trying to track down why my battery is running down so quickly on my iPhone 6s. Is it okay to erase Safari Website Data?
It is perfectly safe to delete Website Data, although that is unlikely to solve your battery life issues. Website Data only include things such as cookies and webpage caches.

If anything, your phone will have to work a little harder to redownload images, log you back in to websites, etc. the first time you visit each site after wiping Website Data.