How many games do I have to lose in a row to demote when I have 0 LP?

i've only demoted like twice, and i deserved them (Was drinking one time)

i think it's 3 or 4

It depends on your mmr. You can lose matches but still perform really well as an individual. For example, you can be at 0 LP at silver 3 but lose like 4 games. But as long as your overall performance is averaging at an S 2 you probably aren’t going to demote. I’ve seen someone slowly decay from S2 to S4 whenever they hit zero in each tier because they just weren’t playing that well. And then I had a time that I lost six in a row at zero and was never demoted because my mmr was sitting where my personal skill was. You can check mmr on op.gg. Just type your name in and then on that screw there should be a little button to check it.