You can disable certain status bar items:

VBoxManage setextradata "VM name"|global GUI/RestrictedStatusBarIndicators OPTION[,OPTION...]

where OPTION is one of the following keywords:

HardDisks

Do not show the hard disk icon in the VM window status bar. By default the hard disk icon is only shown if the VM configuration contains one or more hard disks.

OpticalDisks

Do not show the CD icon in the VM window status bar. By default the CD icon is only shown if the VM configuration contains one or more CD drives.

FloppyDisks

Do not show the floppy icon in the VM window status bar. By default the floppy icon is only shown if the VM configuration contains one or more floppy drives.

Network

Do not show the network icon in the VM window status bar. By default the network icon is only shown if the VM configuration contains one or more active network adapters.

USB

Do not show the USB icon in the status bar.

SharedFolders

Do not show the shared folders icon in the status bar.

Capture

Do not show the capture icon in the status bar.

Features

Do not show the CPU features icon in the status bar.

Mouse

Do not show the mouse icon in the status bar.

Keyboard

Do not show the keyboard icon in the status bar.

This is a per-VM or global setting. Any combination of the above is allowed. If all options are specified, no icons are displayed in the status bar of the VM window. To restore the default behavior, use

VBoxManage setextradata "VM name"|global GUI/RestrictedStatusBarIndicators