Speedometer Cable
Perhaps you mean the hydraulic clutch line? It connects on the driver's side front of the trans, between the bellhousing and the tranny.
You need to push in on the line slightly, and while it's pushed in, push the plastic ring in with a pair of crossed screwdrivers (it's a bit tricky). When you get the plastic ring pushed in a little, pull out on the line, and it pops right out. Most of the time.

