Depending where you live you need the EGR for emissions tests. if you don't need any emission tests. yes you can block them off. I have change the headers on my 2005 Mustang
and the nut that holds the EGR tube to the header can be a pain to get off. what I did is soaked it with an penetrating oil for an hour or so. if that doesn't work heating up the nut with a torch always does the trick.