Salaam Alaykum wa rahmatullahi wa barakatuhu Sheikh. At work, we are building a mobile app and I am team lead. In a coworker's part of the app, on request from our boss, he has to display women with some of their hair uncovered. Am I sinful for supervising this?

Ustadh AbdulAziz al-Haqqan

Supervising it is assisting in it, so it is not allowed. Keep your part of the work to what is free of them.