• Login into the Joomla Administrator at http://yoursite.com/administrator
• Go to Extensions → Install / Uninstall
• Select the Components tab
• Select com_acontact
• Click Uninstall

You must pay attention that the plugins installed with the AContact Manager are not unistalled by default cause can be used from other extensions. So if you dont'use in other extensions, you have to unistall each one.

The  Plugins are:

• Alikonweb IpDetecor

• Alikonweb GoogleMap

• Alikonweb Ajax Captcha Plugin

• Alikonweb Video plugin

So repeat these steps for the plugin you need to uninstall depending on your configuration

• Login into the Joomla Administrator at http://yoursite.com/administrator
• Go to Extensions → Install / Uninstall
• Select the plugin tab
• Select
• Click Uninstall