Before asking a question, first, see FAQ in 3rd post. In that way you can save a lot of time.
For Video Guide refer to 5th Post
You need to disable antivirus before extracting files. Because we are using DirtyCow vulnerability here. Which is technically a virus (It's not dangerous for pc but for exploiting android to get root access). If you can't disable AV then don't proceed because process will not work
2: Minimal adb (2nd post)
A: H830 | For H850 (Refer to this Post and read carefully)
(rename it to recovery.img)
1: Make sure to unlock bootloader. Backup internal data because it will be erased.
A: First enable developer options and toggle “Enable OEM unlock” to ON. Also enable “USB Debugging”.
B: Run Minimal ADB and Fastboot. Enter Command
C: You will see permission dialogue on phone. Tick “Always allow” and ok.
D: Now enter.
adb reboot bootloader
fastboot oem unlock
2: Connect phone with pc in MTP mode and copy recovery.img to phone’s internal storage (Make sure to select MTP as always to avoid problem during procedure). Extract recowvery software. (If it causes permission problems extract it to USB device and perform process from there)
3: Run “EasyRecowvery.cmd”. Press “5” -->Enter then press “7” -->Enter to disable integrity check. Then enter “0” to go back. Skip it if you are using Recowvery G5 modified.
4: Now press “2” and wait until it says warning. Press “y” -->Enter. (It won't say warning in Recowvery G5 modified)
5: It will do rest process. After Flashing TWRP it will flash “no-opt-encrypt” (This is most important to save twrp from being removed by OS)
6: Phone will boot into TWRP. Here on phone it will ask for decrypt code. Cancel it. Swipe to allow modification.
7: On pc press any key, the flashing process on phone will automatically get started. Then it will reboot into OS.
8: To flash supersu, select option 3 from recowvery windows and phone will boot into twrp. Same as step 5-6 it will automatically flash supersu.
Now Your rooted and have twrp install.
Note: For removing Encryption.
To flash a custom rom and remove encryption in twrp, you need to once format data in twrp else you won’t be able to wipe and install any custom rom in your phone.