The ability to limit a user's access to resources is a core feature to CloudLinux, and an important tool for system administrators hosting users in a shared environment. While typically done via the LVE Manager page in WHM, the lvectl command does provide a helpful tool for making changes from command line.
Let's say for example you want to increase the number of Entry Processes for user named "myusername", to a value of 40.
lvectl set-user myusername --maxEntryProcs 40 save
This can be used to set any of the available limitations for an LVE. For a deeper look into the capabilities of this command, see the CloudLinux documentation at: CloudLinux Documentation: Controlling LVE limits