I have downloaded dban software and it gave me the four format methods and when i researched there isn't much difference in security level of (American DoD 5220-22.M, Canadian RCMP TSSIT OPS-II and PRNG Stream methods). therefore, i am looking forwards your opinions as well.
Quick Erase: Fills hard drive with 0's
Gutmann: 27 random-order passes using specific data combined with eight passes using random data.Due to changes in the different data encoding schemes now used by modern hard drives, Gutmann no longer recommends 35 passes. A few random passes should suffice.
American DoD 5220-22.M: A seven-pass wipe using random characters, complements of characters, and random data streams.
Canadian RCMP TSSIT OPS-II: 8 drive-wiping passes with a random byte in the overwrite sequence changed each time.
PRNG Stream methods: Overwrites the drive with a stream from a Pseudo Random Number Generator (PRNG)