Yes, you can be the initial owner and then add other people as owners (or admins). From there you could downgrade yourself to a regular user - or if they're owners, they could downgrade you.

They could also kick you out. I've done this a few times today. We reserved a number of team names for known tech companies, and when they've asked, I've created the team myself, added a couple of their managers as `owner`s, and then they've booted me.

You can think of the team's sigchain as just a string of signed announcements. You can sign someone else in as owner.