Tools>Add-ons from the Firefox menu bar and you can remove it.
And Adobe DOESN'T bundle anything from AVG with ANY of it's downloads or updates, so you didn't get it here.
The products that Adobe DOES bundle are 100% legal to include or they couldn't have included them for more than a decade now.
From where exactly did you download that update?
You are dead wrong! I just applied the update, and I now have the AVG Safe Search toolbar in Firefox, and I am livid. I received the notification in the Vista task bar that an update was ready. I clicked for the install. I was not offered an opt out for anything. Further, your wrong about removing it via the Firefox Addon manager. There is NO remove button, only a disable selection is possible. Further, there is no entry in the Control Panel "Programs & Features uninstaller. I even tried the Advanced System Care 6 Pro uninstaller, which Identified it, but was unable to uninstall it. That is the last update for Adobe that I will install until I hear that they have reversed this insanely insulting method of making money.
"I received the notification in the Vista task bar that an update was ready. I clicked for the install. I was not offered an opt out for anything."
Read this s-l-o-w-l-y and carefully...
You DIDN'T get the update from here. Adobe DOESN'T bundle AVG Anti-virus or ANY AVG product with its updates.
You downloaded from a third party site, probably prompted and linked to through adware.
I'm constantly uninstalling, reinstalling and updating four test machines all week long day-in, day-out, and the ONLY bundled software I've EVER seen (With XP, Vista SP2, WIn7 SP1 and WIn8) are:
Google Chrome (with Google toolbar)
Norton Security scan
McAffee Security Scan
Adobe Lightroom (30 day trial - Mac Only)
You can call me "dead wrong" all you want but REALITY is my source for the info I posted and it will trump ANY argument you can mkae because you DIDN'T download the update with AVG in it from here! Flash Player updates DON'T popup in the Taskbar. Adware and Malware notices about updates DO popup from the taskbar. You were infected before you ever got that"update" and that's NOT Adobe's fault.
If you EVER doubt the genuineness of an update notice ALWAYS go to the software developer DIRECTLY to update. You can check for updates through Flash Player Global Settings (a simple right click on ANY Flash content will get you there) under the Advanced Tab. IF you can't or won't do that, then you DESERVE anything you download without checking it first!