Interesting question. SSHE advocates deleting from the front (in a 9 man game you place a "phantom" 10th player UTG and assume he folded, so in a 7 man game if you are immediately to the left of the blinds you are opening in MP1 after 3 "phantom" folds). This is supported by Ed's "bunching" articles which lead to the conclusion that there is in fact little or no difference between a 10 handed game with UTG-UTG+2 folding and a 7 handed game.

On the other hand King Yao advocates a slightly different approach. I don't remember the details off hand, but he loses something like an MP first then an EP and somewhere along the line an LP. He doesn't explain why.

Although the Yao approach seems logical at first glance and looks balanced in terms of EP/MP/LP, the SSHE approach is more compelling. As previously mentioned by someone else, the EP/MP and LP labels are primarily to define where you are in relation to the button. If you are 4 off the button in a 7 handed game you are first to act, but it makes more sense to consider MP opening hands rather than the tighter EP opening hands because the only reason for having tighter EP opening standards is to take into account the larger number of players yet to act.