First, install Virtuemart language for you own country Second, check this file : language/en-GB/en-GB.tpl_gk_storebox.ini where you find: TPL_GK_LANG_MY_CART="My Cart"
I have strange felling that you are asking us(me) about how to use Virtuemart, instead read book/articles about VM or search on virtemart forum. Sure you can hide using CSS, but check VM settings first.