An answer maybe found here...
Text..
I just up-graded to a 22"Mitsubishi, a lease pull. I did cold boot it twice and that should have been enough to degauss
it. I played with all the controls for display properties and was not happy with my results.
Low & behold !! A degauss button in OSD. I set everything back to default, hit the degauss button and presto...change-o.
From what I have read a cold boot of the monitor will do it but booting from wake-up won't. The site above warns against using this feature repetitively on Sonys as the coil will over heat.
I now believe another monitor was degaussed next to mine, after mine was done. This will have a negative impact
on to one that was done.
When a TV is turned on cold, that booinnng sound is the degauss process.
Check Sony's web page and see what they offer. NEC/Mitsubishi offers Naviset, BenSkywalker noted this in a post
and I'm glad I downloaded it