Pretty sure it's just a bug. I remember someone having a similar complaint years ago, but I forgot the details. Maybe it's best you file a bug report and see what they say.

yes, it's confirmed, it's the 4th time today. Deleted yesterday morning but he's back again in my friendlist tonight. The issue happening against a specific player only .... If I remove someone else, they are just removed asusual. But he creeps into my friendlist somehow, How do I prove this with screenshot/s ?

I wouldn't. I would explain what's going on and specify which player in my friends list is the problem. The Support can enter your acc and see for themselves.

What I would expect to happen - and I could be wrong - is that they'll remove the friend and tell you it's resolved. Then, when the person pops back in, you'll respond that they are back without an approval from you. Then they'll look deeper into it. I hope I'm wrong and it's easier. Good luck!