Sumo has no free agency.
Once a man enters a stable there is no system in place to allow transfers to a different one.
Of course wrestlers do sometimes move, but only when their original heya (stable) closes down or the oyakata (sumo elder) who recruited them branches out to set up his own establishment.
With your current subscription plan you can comment on stories. However, before writing your first comment, please create a display name in the Profile section of your subscriber account page.