As part of their punishment by the rulers of the empire, the renegades had their personality components removed from their structures, their bodies, and were placed within the Decepticon Detention Center. There they would remain powerless as their structures were destroyed to prevent them from becoming a threat.
Certain personality structures had been imprisoned for millions of years and could only influence the corporeal world if new bodies were built for them.
Considering the number of cells located in the Detention Center, it's entirely possible that further renegades were present on Cybertron for various crimes.
The Transformers cartoon
After Starscream was banished from the Decepticon headquarters for attempting to usurp command from Megatron, he journeyed through the Space Bridge to Cybertron where he looked for Cell 217 in the Decepticon Detention Center. After locating the prison cell, he "liberated" the personality components and destroyed the rest of the cell in order to produce his own personal army. These "renegades" would become the Combaticons who had been imprisoned on Cybertron for millions of years and worked to get their revenge on Megatron.