Well I think they normally install these to filter noise from reaching your receiver when using the built in BEC. But most likely you are not using the BEC on a multirotor so I would say it is safe to remove them. I had these installed on some f-30a esc when I recieved them and later removed them with no Ill effect. But I am not using the BEC either. I also think the ferrite ring was more for people using the 72mhz band for Rx/Tx. This is my opinion on the ferrite rings on escs.