Im also having same issue on a IPhone SE (IOS 10.3.3) re persistent 0Kb cookies if Website data not deleting. Does anyone:
(a) know of a Windows solution eg some effective third party software? (Some software claims to be able to do this, but it will cost about 20- 50 USD to buy software !!! (and no guarantee it will do job)
(b) a solution in Safari/ on Phone itself. (All the answers seem to focus on Macs eg using Finder/ Databases etc and unfortunately Ive not got one). Some solutions say revisit the offending (cookie) website and allow cookies, then delete Website data with the cookie website open. However, this has not worked for me. Its been a very annoying process.
I dont want to upgrade to IOS 11.2 etc as its too heavy in battery etc and Im not sure if it will even resolve the problem.
If anyone can help with a or b that would be most appreciated.