How to Delete Fota files

Step 1: Download the files to your computer and upload them to your your phone.

Step 2: Install any ROOT File Expert

Step 3:  Make sure that the File Explorer can mount and write on the ROM system files.

Step 4: Extract fota.zip file and select Unzipped fota files (fota_delta_dp1 and fota_delta_dp2) to /data/fota or paste the 2 files in this folder

Step 5: Reboot phone

WALLA!!

Now check your free space in the ROM.