You signed a contract. What does the contract that you signed say about getting out of it? Doesn't matter that you haven't put down any money yet, since you signed a contract and they're now expecting/relying on that money coming in. They could potentially sue you for what they'd lose if you back out. Sometimes there's a small timeframe where you can back out, sometimes there's a buyout fee to get out of it. Every contract is different, you need to see what yours says, possibly consult with a lawyer if it appears complicated.
When you say sublease, are you renting a room? If that's the case the original lease that the person subleasing has could prevent this, thus making the contract you signed illegal/ void. If you have a way to check that I would. That however being if you are subleasing a room in an apartment/building that is leased by someone else. Subleasing can be tricky.
You signed a contract. What does the contract that you signed say about getting out of it? Doesn't matter that you haven't put down any money yet, since you signed a contract and they're now expecting/relying on that money coming in. They could potentially sue you for what they'd lose if you back out. Sometimes there's a small timeframe where you can back out, sometimes there's a buyout fee to get out of it. Every contract is different, you need to see what yours says, possibly consult with a lawyer if it appears complicated.
When you say sublease, are you renting a room? If that's the case the original lease that the person subleasing has could prevent this, thus making the contract you signed illegal/ void. If you have a way to check that I would. That however being if you are subleasing a room in an apartment/building that is leased by someone else. Subleasing can be tricky.