Let's talk about Proof of Work which is what Bitcoin uses (Ethereum uses Proof of Stake, and that's slightly different).

The way Blockchain works is that every block depends on the previous one, I won't bother with the mathematics of it, just accept that a block needs to have a parent block. The protocol is that the longest chain is the valid one, once your transaction gets on a block miners are incentivized to build on top of that. In short, suppose the chain currently has 100 blocks, your transaction on block 101, a miner that purposefully ignores that block to try to build a different 101 block is racing against every other miner who's trying to build block 102, because I'd any other miner builds 102 before then he now needs to build 2 blocks before the miners build 1, so on and so forth until he has to accept defeat.

In short, a single miner depends on luck to be able to "rollback" (it's not really a rollback, it's a pretend it never happened and move the tokens elsewhere so the original transaction is not valid, in an attack called double-spending). This is why the more blocks (or verifications) are on top of a transaction the harder it is to "revert". To "undo" a transaction that just happened you have to get lucky twice and build two blocks in quick succession, to undo a transaction from an hour ago you have to build 7 blocks in average before others can build one. To give you an idea of just how unfeasible this is, the reward for finding a Bitcoin block is around $80.000 currently, this means that to "undo" a transaction that happened 1 hour you're losing the opportunity to earn over half a million dollars (which is what you would earn if you were to find 7 blocks without having to race against anyone else)

Because no one has your private keys, the only way to move the tokens from your ownership is to rollback the chain until that transaction happened, remove it, and rebuild the chain from that point onwards. So, it's doable, in the sense that it's physically possible, but unless you can convince the majority of miners that the transaction should be reverted, and even then until the new chain reaches or surpasses the old one the old one is the valid one, so if you only convince 51% of miners and the transaction happened a few hours ago they'll probably spend a few days catching up, and if in the meantime some miners flip side they might never catch it and miners might abandon your cause as it's coating them 80 thousand dollars every time someone else finds a block.

Finally, if such a thing were to actually happen, trust in that coin would drop significantly, and with that its price, and with that the money minera receive from finding blocks. So it's not in their best interest to do that, as it can yield to them losing money from their source of income.

In short, yes, it's possible, but unless your attacker can essentially burn millions of dollars to fuck with you it's not very likely to happen.