Notification of non-renewal of contract (for the next season)
Notification of the team's intent not to make a contract for the next season)
Notice of non-inclusion in the team (for the next season)
●「通告」notification, notice
●「戦力外」→(来シーズンへの)「契約更改無し」non-renewal of contract, または、「チームの(来シーズンの)契約を結ば
ない意志」the team's intent not to make a contract, または、
(来シーズンは)チームに含めない(含まれない)non-inclusion
in the team