Hi, I'm Anvar, I'd be glad to help you today on this
Click on the Custom: Install Windows only (Advanced) option clean install windows on the drive , which will get rid of bitlocker encryption as below steps remove all data on the disk
Select the partition with the current installation (usually "Drive 0"), and click the Delete button.
Quick tip: If "Drive 0" has multiple partitions, you have to select and delete each of the partitions to allow the setup to use the entire drive for the new clean installation. Windows 10 will create the required partitions automatically during the process. It's not necessary to delete the partitions on secondary drives.
Click the Yes button.
Select the empty drive (Drive 0 Unallocated Space).
Click the Next button.
Once you complete the steps, the setup will proceed with the fresh installation of Windows 10 on the device.
Hope this helps.