Awake,

Yes, you can delete the entries in the Log Viewer if you feel you do not need them anymore.
But I would caution you here…
Make sure that you have addressed any Error or Alert that shows first!

You can delete any entry by highlighting it, right clicking and selecting Delete.

The Log Viewer is only for administrative purposes and does not affect the operation of Avast.

By the way…What are MBs? ;D

Techie