if switch from Guild master to player, will I lose my progress so far?
If you mean your game progress, no. You won’t lose anything by giving up your role as guild master.
Guild Masters get no more opportunities or rewards than the players. Most times, they do take on a lot of responsibility though. GMs or GLs, however you may wanna call them, are awesome. Mostly .
By the way, RiverSong already answered your question. So I got nothing more to add there.
You don’t have to disband a guild to leave it; if you do, whomever is second-in-command will inherit the GM rank.
If you are the only one in your guild, you might want to create an alt and leave it in charge, just in case you ever want to return.
Guild Seals, Trophies, and Gold Donated will all be reset once you enter a new guild, but that information isn’t as important as having fun, and doesn’t impact your play performance.