I dont think he can remove curses yet? He just stopped the curse-warding "spell" exploding life.
Asta has a sword that not only nullifies magic but also it's effects...the causality sword. It turned the elf possessed back into their true selves and healed the priest at the orphanage from a poison magic attack. Note Asta did not have that sword back when his arms were cursed and he needed the witch queen...
Lolo was a victim of curse magic and that curse was recently manipulated to make her devil possessed and then into a devil. Those last panels show him hitting lolo right in the spot of where she was originally cursed. He obviously stopped her from blowing up, but she still looks like a devil so I can't be sure how much his anti magic has helped yet.
Sorry but can someone tell me why he didn't remove lolo's curse back when they were training in the heart kingdom?