How to Delete Partition and Extend C Drive Windows 10

Usually, C drive is the system partition. If C drive is running out of space, your computer can run slowly and be unable to react to commands immediately, or your computer screen is gray and not work at all. Therefore, extending C drive is necessary if it is almost full. This guide will introduce two ways to extend C drive:

• Use disk management tools to merge drive C with another drive (e.g. D, E or F). This method requires deleting the D partition first, which may result in data loss.
• With AOMEI Partition Assistant, add unallocated space to the C drive partition to extend the C drive without deleting the partition. This method can expand Windows C drive space quickly and efficiently, and you will not lose any data.

Delete partition and extend C drive: Why and how?

When the hard drive has unallocated space adjacent to C drive, you can extend it easily via Extend Volume in Disk Management. However, once there is no such space, Extend Volume greyed out will be greyed out. You may consider shrink partition to gain unallocated space. And you’ll find that the unallocated space is behind the shrunk partition rather than C drive.

To get a contiguous space behind C drive, you need to delete the partition of the exact position to make it unallocated space. Then, you can extend C drive with the unallocated space.

Step 1. Here, D drive is the partition which is behind and adjacent to C drive. Right-click D drive and select "Delete Volume".

There will be a pop-up window, which will note you that this operation will erase all the data on D drive, and select “YES”. If there are some important data on it, you need to backup first with AOMEI Backupper.

Step 2. Right click C drive and select "Extend Volume".

Delete partition but Extend Volume is still greyed out?

Why can't extend the C drive with unallocated space in Windows 10?

If the partition right behind C drive is an extended partition with multiple logical partitions, you still can’t extend C drive even though you delete the logical partition adjacent behind C drive. This is because what you get is a free pace, not an unallocated space. You need to delete all the logical drives on the extended partition. Then, delete the extended partition to get an unallocated space for extending C drive.

An easier way to extend C drive [without deleting]

Here I’d introduce you to powerful & overall partition manager – AOMEI Partition Assistant Standard, which allows you to extend partitions without deleting any partition. If there is free or unallocated space but not adjacent, you can use Merge Partitions function to extend C drive. If there is no free or unallocated space, you can use the Resize Partition and Merge Partitions functions to enlarge the C drive.

This tool has a simple interface and it's easy for all to extend partition. Now, free download this software and do the steps given below (supposed that there is no free or unallocated space on the same disk):

Step 1. Install and run the software. Right-click the partition with enough free space (here is partition F) and choose Resize/Move Partition.

Step 2. In the pop-up window, point your mouse on the left board and drag it toward the right side to shrink so as to get unallocated space, or you can input the exact number. Then click “OK” to continue.

Step 3. Right-click C drive to select “Merge Partitions" under "Advanced". In the pop-up window, tick Unallocated and click Next.

Step 4. Click Apply and Proceed to commit operation.

Then, you’ll see that the C drive has been extended without removing the partition. You can also use App Mover to move space from D drive to C drive windows 10.

Notes:
● AOMEI Partition Assistant Standard supports all Windows editions including Windows7\8\8.1\10\XP\Vista of both 32bit and 64bit.
● To enjoy more features, such as App Mover, Allocate Free Space, clone MBR system disk to GPT, etc., you can upgrade to Professional Edition.

AOMEI Partition Assistant provides many additional features to manage hard drive and improve computer performance, such as running disk surface test to check and repair bad sectors, using app mover to free up space, converting disks. Download it and enjoy the benefits it brings to you.

Final words

You can delete partition to get adjacent space behind C drive and then extend it within Disk Management; or extend C drive through adding non-unallocated space into C drive. Make your decision based on the specific situation.