My friend accidentally placed two tesseracks and it is bound to him; he is the owner of it, and i want to clear ownership and i tried to break with pickaxe and used a wrench. Both ways did not remove owner ship were as breaking the tesseracks with a pick should remove ownership but did not.
If that would reset ownership, it would defeat the whole purpose of the possibilities of securing it so well. As far as I know, you cannot change the ownership of the Tesseract, not even the owner himself. He is the only one however, who could change the security to allow access by all players. This would also mean anyone else who might be trusted on the island can access it, so that's something to think about.
Only way for you to be able to access it is if your friend changes the access so that everyone can access it (you can do this in the UI) however, that also means that anyone else that is trusted in your claim is also going to be able to access it
Actually in this kind of situation, a (co)admin can use creative mode to delete the existing private tesseract and then give the island owner a fresh creatively spawned one that isn't attached to a specific player yet. @Xaryu could you please tell me which CL server you are on, and I will replace the tesseracts for you as soon as I get chance to.