Dual boot to single boot

I currently have a dual boot system(Windows 10+Fedora 33) on one 512GB SSD with 2 main partitions and I want to remove the Windows 10. My question is: Do I have to format the drive and reinstall Fedora or can I just delete the Windows partitions(I have a C: and a D: and one more small partition which I don’t know what it is for)?

Assuming your system is installed with efi boot you do not want to remove that partition. You can, however, use “sudo gparted” and display all the partitions and their types. Once you have identified all the partitions that are windows related then those can be deleted to erase windows.
There likely are (as a minimum) 3 partitions in addition to the efi partition. If they show as ntfs they are windows. On my system, when I open gparted to look at the drive I see a “microsoft reserved partition” (formatted unknown) and 2 “basic data partitions” (formatted ntfs) as well as the “EFI system partition” and the linux partitions.
Removing the 3 windows partitions (Not the ESP) then rebooting should be all that is needed. There is another step if you want to remove windows from your grub boot menu immediately but that should be automatically taken care of with the next kernel update anyway.

Thank you very much!