City signed left-sided defender Ryley in July 2025, paying Sky Bet Championship side Portsmouth an undisclosed fee to complete the transfer.
Towler was part of the Pompey side that landed the Sky Bet League One title in the 2023/24 campaign and featured 14 times in all competitions last term as they retained their second tier status.
The 23-year-old came through the ranks at his hometown club Bristol City. During his time with the Robins he furthered his footballing development with loan spells at the likes of Grimsby Town and AFC Wimbledon.