how do u pronounce "often"?

Either with a "t" or without a "t" is correct both in the USA or England. I don't know about other English-speaking regions including other areas of the United Kingdom.

I've lived in Southern California my whole life and most people I know, including myself, pronounce of-ten. I pronounce it with the "T" sound. Either way works though.

/Af@n/ for me

I pronounce it as ofen.

It's not wrong to pronounce the "t"; It's pronounced with the "t" in both
GB and the USA. Check a couple of dictionaries. It's also okay not to pronounce the "t".