Mixcraft has two files, which you can edit to exclude plug-ins from loading. These files are located in %programdata%\Acoustica\Mixcraft\ folder.
DXIgnore.ini - DirectX effect ignore list
VSTIgnore.ini - VST plug-in ignore list
Simply open or double click the file and then add the name of the effect and set it to equal = 1. For example, if you had an effect called 'Digital Media StudioDenoiser' that you didn't want the software to load, you would enter
Digital Media StudioDenoiser=1
Save the ignore file and restart Mixcraft and the effect will not be loaded. For VST plug-ins, you will need to use the name of the dll such as SuperDuperReverb.dll=1