First-half goals by Dean Cox and Moses Odubajo, the latter making his first league start, gave the O's only their sixth home win of the season.
Reece Gray pulled a goal back for Rochdale but Orient held on to record the double over their opponents, who return to npower League Two after two seasons at the higher level.
"All the players have been told who is staying and who is going although I'm not sure whether the club have released the news yet," he said.
"The manager (John Coleman) and I have already started the work towards next season, in fact it started a couple of weeks ago.
"We've got targets, we need to rebuild a different ethic of how to approach games. It seems that since we've been here whenever we get out under pressure, we concede a goal and then another."