All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.
As long as you knew the purpose for which the logo was designed and that it would be placed on such revealing clothes that are to be worn by indecently dressed girls at the beach, then you should not have designed it. The fact that your boss asked you to design it does not make it permissible for you to do so. Designing the logo by itself does not waive the sin given that you knew the purpose for it. Allah, The Exalted, says (what means): {...and do not cooperate in sin and aggression...} [Quran 5:2]
So ask Allah for forgiveness and resolve never to do such work again. For more benefit, please refer to fatwa 86527.
Allah knows best.