How to select multiple lines in Sublime Text (quickly)

I have a JS file that has over 100000 lines of code, I want to get rid of the first 25000, I’ve been trying hard but can’t figure out how do I select them all at once (holding left mouse button and scrolling down is not an option as it would take forever). I guess holding SHIFT and arrow DOWN is the way to go, but I have absolutely no idea how to select them all at once anyway. Maybe selecting 25000th line, pressing shift, left arrow and then HOME would help, but I’m working on OS X and have