A lot of folks don't like the constant leak when the motor is running from the chain oiler.
(or the draining of the tube on the floor when shut down)
As long as the threads on the fittings will seal, you can simply turn the adjustment screw (clockwise) to a light seat to stop the oil flow.
Or you can plug the oil path at the source (right engine case or oil tank respectively).
You can either plug the fitting at the source with a bolt / screw or remove the fitting and install a 1/8“x27 NPT plug in the case.
Then you'll need to oil the chain by other means (chain wax, other).
You can also run an alternate hose from the crankcase breather pipe back to oil the chain (mostly oil mist at best from the breather).
However, it is far better to use a good quality chain wax. It won't fling off all over the bike or rear tire. ¹⁾

73-Up right case half 2)	Chain oiler on 1976 XLCH 3)