What is this thing?

I’m trying to replace the wheel cylinder and while I was removing the brake line the bolt got stuck on this thing, preventing me from removing it all the way. What is this thing and what does it do? Is it safe to remove? https://imgur.com/m9FKQ4X

That is the Ball Joint that attaches to the A-arm.
The grease fitting at the bottom of the ball joint can me taken off and put back on no problem it’s not under pressure no big deal to remove.