The Laptop or desktop comes with per-loaded OS which has OS recovery partition where the recovery files have saved. If the user wants delete that partition in disk management utility, then the delete option is not available.

Here is the tutorial show you how to delete the recovery partition where the delete option is not available in disk management utility. This can be achieved by Disk Part tool.
Please perform the following steps:

recovery partition in windows 8

1. Open a command prompt as administrator.

2. Run Diskpart application by typing Diskpart in the command prompt.

3. In the “Diskpart” prompt, Type in list disk and press Enter key to show all hard disk drive available.

4. Select the disk that contains the partition you want to remove. In this tutorial, I have two hard disk and recovery partition is present in disk 1. So the command will be:

5. Select disk 1 and press Enter key.

6. Type list partition and press Enter key to show all available and created partition in the disk selected.

7. Select the partition that wanted to be deleted by using the following command, followed by Enter key:

Select partition x

Where x is the number of the recovery partition to be removed and unlocked its space. Be careful with the number of this partition, as wrong number may get data wipes off.

8. Finally, type in delete partition override and press Enter key.

diskpart to delete recovery partition  in windows 8