In general, it's possible to revert DD-WRT firmware to your router's stock firmware. For many models, this option is accessible from DD-WRT's Web interface. However, you should know that not every model supports this action.
Trying to 'downgrade' from DD-WRT to your router's stock firmware comes with certain dangers. Some features might not work properly, or you can end up with a bricked device. This is why we recommend letting an expert perform this, or making sure you have clear and 100% valid instructions.