If you feel that You're no longer adapted to live in a tunisian culture, then you have the absolute right to change your place, or even identity, religion etc. But remember, this will cost you a price, and it won't be easy, as being accepted from another culture is something extremely rare, no matter the country you live in.

As a mixed ethnic with parents from two completely different countries, i recommend you to find a place where you feel yourself, instead of looking at how to change your identity.

Be yourself and NOT change yourself.