At the start of a new WPS Season, you will begin at a Division that is one rank lower than the Division you finished at during the previous season.
(For example, if you finish at Division 2 in Season 1, you will start at Division 3 in Season 2.)
Therefore, please keep in mind that this is an intended game mechanic.
In addition, you will not get relegated when you finish at Division 10.
From Master 3 to Master 1, promotions, staying up, and relegations will be determined by your ranking. In addition, you cannot get relegated from Master 3 to a Division.