WTA, my current BTU modem and router is located at 1st floor, the fiber wire is running from backyard's tm box directly to 1st floor, if i want to move my modem and router to ground floor, can i just pull out the fiber plug by my self and reconnect?

Pull out from BTU can. But to pull out from TM fibre box I think you cannot do that. Less something broken, TM will blame you.

1. Yes you can remove the fiber cable from the BTU, but you have to know how to do it properly. 1 wrong move and you'll break the cable
2. Make sure the length of the fiber cable to the ground floor is the same, if not, then you might have to buy your own cable