I (sort of) recently got a new violin and as the tailpiece does not match my earlier rental I now have a mismatched ball end E string from my extra set. Looking at the string it definitely seems like I could carefully remove the ball without a huge amount of effort, despite it not being advertised as removable. It doesn't look especially tightly wound around the ball. Is it safe to remove the ball and use the string on with my new tailpiece?
I tried this once in a similar predicament and was not left with a tidy loop of wire but with an unraveled mess. However, you can use an adapter like this one to use the ball-end string with a loop-end fine tuner.
Counterpoint: I've seen some E strings ship with a loop end in which a ball has been placed, so they could accommodate either need. In that case, you can absolutely simply pop the ball out of the loop.
So give it a shot! A pair of tweezers or needle-nose pliers could help. If it seems like the wire is too tightly integrated, you could go the adapter route.
It should very well be possible to remove the ball on some strings, so if you do not have another use for a ball end e string, then just try it! As long as the string is not damaged or bend during this process this should be safe enough.
But considering the price of a string you might simply give your new violin a new string. I would advice against getting an adapter as Andy suggested as such an adapter will cost not much less or even more than most e strings and will most likely affect the sound. The only reason I see for using such an adapter is if you want to use a very specific string that is only sold with ball end. But even in this case you could simply chance the fine tuner.