SAP2000 modelling 1

It all depends on what exactly you want to do.

Do you want to model a support that doesn't translate along X, Y, and Z axis? Then pin it.
Do you want to model a support that doesn't translate along X and Z axis? but translate in Y axis? Then assign a roller or release restraint.

Using a pin support is enough as you wouldn't want it to move around.

The thing is I want it to translate in the Z direction only upwards and not downwards. Since its just placed on the ground without a mechanical connection
Thank you!

This kind of connection can really only be achieved with a "Gap" link element, which essentially provides bearing restraint but not uplift restraint. This will require you to run your load cases/combinations as nonlinear static cases

Depending on your structure, if you don't expect the loading to produce uplift, you could just pin it and ensure uplift is not developed at any of the supports, which is essentially the same thing. But if you are going to get uplift, the only way to "release" it in one direction is with a gap link, or a hook link for the opposite case