Convert NTFS filesystem to ext4 without losing data

Is there any ways to convert NTFS filesystem to ext4 in linux without losing data?
No .. You cannot "convert" from NTFS to ext4 directly.

There are 2 options​

1. Using another hard disk
a. Copy data to temporary another disk
b. Delete the NTFS Partition
c. Create EXT4 Partition
d. Copy data back from the temporary disk.

2. Second method
a. Shrink the NTFS
b. create EXT4
c. copy data to EXT4
d. shrink NTFS
e. grow EXT4
f. copy data to EXT4
g. do the shrinking
h. growing and copying until all data is copied
i. then delete NTFS volume.