Ramming submarines was an escort tactic

Did Flower-class sloops and other anti-submarine escorts use ramming tactics against submarines?

Yes. Ramming was part of anti-submarine doctrine and was attempted by dedicated escort vessels as well as by famous larger ships.

Ramming was part of World War I anti-submarine doctrine. The tactic is often remembered through HMS Dreadnought's famous sinking of U-29, which can make it seem exceptional. Ships assigned to anti-submarine work were also expected to attempt it. Their low-speed escort role and close contact with surfaced submarines made ramming one available method alongside gunfire and depth charges.