Yes, your BIFI will still stay in your wallet if you delegate them. Delegation means that you are giving the governance voting power of your BIFI (staked or held in wallet) to someone else. This means that you are still in control of the BIFI tokens, but you are allowing someone else to use the voting power of your tokens. This allows you to keep your tokens safe in your wallet while still being able to participate in the governance of the BIFI network.