I'm fairly confused about how to get demoted with being protected?

Okay, um i have lost about 18 games and i'm at silver rank 5. even before the lost games i was already at the 0 lp but after around the fifth loss there was a thingy above my-where it says silver5 on the lobby, and it was like "you are being protected from getting demoted please do not lose anymore games or you will be demoted." so I just kinda did the same thing i'm used to, and...lost again. BUT, the game wouldn't let me drop, so then i figured that, okay maybe its taking out points for the next time i win right? and so i won my game and i got like 17 lp and i thought"okay so if i don't lose these points i'll be protected by the alert warning thingy again." and ugh, i found out i was wrong because i kept not winning the games...another 13 times but the game is not letting me drop, so i need help understanding the, how the ranked dropping works please.