When you delegate your XRD tokens to a validator node, those tokens enter a special “staked” state enforced by the Radix protocol. You can’t do anything with those tokens while they are in that state. They are “illiquid”.
However, you do still own them, and you can unstake them at any time, after an unstaking delay period required for security.
Your tokens are never under the control of the node you stake to. Delegating tokens is just a way of “voting” for which node-runners you want to be in the validator set.