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@Venutus1. I have the quad fixture with the Arcadia T5's. The bulbs simply pull straight down from their metal clamps. Usually they will come out with just a little downward pull. Do one side of the bulb at a time. The plugs on the end slide right off. To re-install, just do the reverse. One side at a time. I do one bulb at a time so the wires don't get mixed up.
If you have the type that plugs into one side of the fixture, the metal clamps hold the bulb in place on the opposite side. You should be able to gently pull the bulbs free from the metal holders and then pull the bulb straight out of its socket. I don't have that type, but that's how they generally work.