Hi,
1- Browse your "Plugin Manager" and find the "Flexible VM2 Template" plugin, in the parameter find this field: "Special Offer Box" and leave it blank (completely blank, don't even put a space or DOT in those fields). Then the "special offer box" will be gone.
2- The "Product Details" TAB is a MUST, you can't remove it, but if you disable RATINGS from virtuemart congifuration, the rating tab will be gone. Same idea for "related products" and "related categories", if you don't have related things, those TABS won't be show off. And Again, go to "Flexible VM2 Template" plugin, and don't put anything in the fields for "Custom Tab-1 - Title" and "Custom Tab-2 - Title" those TABS (shipping and Q&A TABs) will be gone as well.
Ohh by the way, Can't you remove completely those fields in the "Flexible VM2 Template" plugin? They get back to "default values" when you leave them blank? Then probably you have the old version. That issue is fixed in the new version of plugin. They don't get the default values when they are left blank anymore, if this is the case let me know and i will send you the new version for plugin.
Cheers.