Rehabbing 20X40 vinyl pool. One Pool company said i dont need main drain remove it. The other said its the only way to cirulate water in deep end. Not sure depth of deep end maybe 8- 9 ft. I have 2 skimmers and 4 returns. leaning towards no main drain due to cost savings Any thoughts? will i have trouble keeping pool clean/clear without main?

It is nice for a few things, but you don't absolutely need it. If you have an automatic cleaner that runs regularly, I wouldn't be concerned at all.

I don't have one installed and the only issue I get is minor dirt bugs that sink down there. Nothing a quick vacuum can't pick up.
I'm sure it would be nice to drain the pool at the end of the season, but I use an external pump for that.