Milton Keynes Dons will be playing Sky Bet League 1 football next season after falling to a crushing 4-1 defeat against Brentford.
"I don't really know - I think it's numbness really," Robinson told MK Dons Player HD, after being asked for his feelings following relegation.
"We've worked so hard to try and get something out of this season and for your fate to finally be decided, especially in the way it was today - we've conceded eight goals at home in the last two games - is diabolical and not acceptable.
"A lot of people at this football club have let themselves down. I think it's time for an overhaul all over the football club.
"I think it's time to move forward. People who have been here for a long time need to stand up and be counted more.
"And on the pitch, I think it's maybe the end of an era to an extent."