If i attack with daenerys then naval in the fleet and remove daenerys from the challenge does her effect still resolve? Daenerys says ... If you win the challenge kill that character.

Just to help answer the question, here is her full text:

" Response : After you declare Daenerys Targaryen as an attacker, choose a character without attachments controlled by defending player. If you win the challenge, kill that character."

I understand that in order to trigger her effect, she must be declared as an attacker first. Once that happens, her effect will continue because it does not specify that she must be participating in order to kill the character. Her lasting effect will persist until the challenge is over or until the chosen character is removed from play.