New to RGB LED's. Will this work? It is working on the simulator.

 

It looks as though it should work, but no two LEDs have exactly the same forward voltage/current characteristics so you may see a slight difference in their intensities, running them in parallel with a common series resistor.

 

Will this work?

Not advisable to wire LEDs in parallel unless the forward voltages are matched closely enough.

It is working on the simulator.

Simulator doesn't necessarily reflect reality. It's up to the user to sanity check results.

Why did you draw your schematic upside down?

 

Don't put leds in parallel without their own series resistor, your leds are all wired together sharing the same resistance.

Ideally use a Constant current source per each led.

 

View attachment 314943
New to RGB LED's. Will this work? It is working on the simulator.

Probably.
But it would work better if you use 620Ω resistors instead of the 100Ω resistors, one per LED and join them all together at the rheostat wiper.
The other disadvantage is that even at the highest resistance on the rheostat the LEDs will be illuminated. The response of the eye to light is logarithmic, so very small currents are visible.