My advise as a Swiss living in Africa.
Dont withdraw yr AHV!
If you have to take out yr bvg ok but thats also not such a great idea?
Why? Ahv stays forever & when u r pensioned or disabled u get something. If possible continue paying in. If u work in EU yr pension there can be combined with ahv. (Eu agreement)
Bvg has good interest ( better than 0)