Disabling Brute force protection within your cPanel/WHM configuration isn't complicated and only takes a few steps. To do this please follow the step-by-step direction outlined below for your convenience.
[1] Login to your WHM (Web Host Manager)
[2] Next locate the section entitled "Security Center"
[3] Then, click on the "cPHulk Brute Force Protection" link.
[4] Next, locate "cPHulk is currently Enabled" and click on "Disable" button.
[5] Finally, click on "Flush DB" button to remove previous records.
After completing above mentioned steps, You can able to access cPanel accounts without any problems.