It depends as to what stage of the transaction you are in. Have you received signed seller acceptance of the offer or just verbal acceptance? You really need to discuss this with your realtor so that they can best help you with your buyers remorse (which is not uncommon).
If everything is signed sealed and delivered then you are now entered into a legal contract and will need to review and understand the contract to find if you do have an "out". Usually inspections, appraisals, Approval of CCR's and of course ability to obtain financing are reasons to withdraw/cancel. Hopefully, things will look clearer after you speak with your agent.
Realtor, GRI, CSSN
John Hall & Associates