You can leave it in your account until you can pay. The tax filing deadline for your 2023 tax return is April 30, 2024. If you or your spouse is self-employed, then your taxes are not due until Jun 15, 2024, though you still have to pay any taxes owing by April 30th.
If you want to delete your return, click the small Trash Can next to it or “Delete” under the return’s name.
If you only have one return, then you'll need to start another return before you can delete the first one. To start a new return, select “Start a New Return” from under “My Returns” in the top left corner. Once you have started your new return, you can select “View All Returns” from under “My Accounts & Returns”. Then delete the unwanted return by clicking the small Trash Can next to it or “Delete” under the return’s name.