phaius tankervilleae, potting mix
 

I got this orchid last year and potted in regular garden soil. Now that I have more experience I realize that it should probably go in a mix for cymbidium's.
My question relates to removing the pseudobulb's. I have a few that are old and the plant is really big so I am wondering if its okay to remove them. They are green but only one has growth on it.
I need to repot this asap.
Thanks

Mine is just in Pro-Mix. It is a terrestrial. Might be worth mixing in some lava rock if you can find it. Tankervilleae grows wild on many of the Hawaiian Islands so that would be natural.

As far as the backbulbs go, yes, you can remove them but they are still providing nutrients to the main part of the plant. Unless you don't want to up-pot to accommodate them as they are, I'd just remove maybe half of them furthest from the new growth.
If you want, you can try and get the backbulbs to start another plant.

In my opinion, anything that is green is still contributing to the welfare of the colony, so should be left attached, if that is practical and if removing them still leaves you with 2 or 3 old growths plus at least one new one.

I have found Phaius tankervilleae to grow well in "peat lite" soils, very sandy soils, and semi-hydroponics

This is a true terrestrial, so a light soil type mix is recommended (and also what I use for my 500+ Cymbidiums).

If you study Cymbidiums, half the species are epiphytes and half are terrestrials. The modern hybrids we see have a mix of both in the background, but they are doing perfectly well in a light semi-terrestrial mix.

I can no longer get my preferred primary ingredient (chunky peat, in 1/2" to 2" nuggets), so for last two years I have been using:
4 parts mulch (cedar if I can get it)
3 parts composted cow manure
1 part bark
1 part perlite

For Phaiocalanthes & deciduous Calanthes, I use Promix in place of the mulch, all the other ingredients remain the same.

i have mine in a mix like my cyms- it is mostly peat and small perlite with charcoal and lava rock as well.

I really like the idea of using mulch and manure like Kim does and i will be adding that on my next batch.

I grow my cyms without the small perlite and with huge perlite instead but i have a different climate than kim