Step 1. Login to server directly using ssh example: ssh root@192.168.0.120
Step 2. Copy and paste this code, line by line
racadm set iDRAC.Users.4.Username USERNAME
racadm set iDRAC.Users.4.Password NewPassword
racadm set iDRAC.Users.4.Enable 1
racadm set iDRAC.Users.4.Privilege 0x1ff
Integral values:
2 — User Privilege=0x1
3 — Operator Privilege=0x1f3
4 — Administrator Privilege=0x1ff
15 — No access Privilege=0x0
Ps. 4 is a number in idrac, it could be another ex.5 or 6