Bleeding the coolant system?

[91 318is]

I tried searching but came up with nothing.

I did the heater plate delete and I've been trying to bleed it for about 30 minutes and not having too much luck. When I run the heater on full hot, it's blowing cold, so I know there's air in the system. Is it better to run it with the cap off or should I put the cap on and let the system pressurized? When I leave the cap off, the temperature doesn't get too hot, but it just pumps coolant out of the overflow. When I cap it, it begins to overheat and I shut it off.

Any advice?