The phrase "previous regime" refers to the governing system or leadership that was in place before the current one. It implies a change of power or authority from the old leadership to the new. Full definition
He said there was still uncertainty about which role the board was performing in the case of a diminishing number of prisoners sentenced under previous regimes. (newlawjournal.co.uk)
One of the key problems that has been prevalent has been a lack of balance in the side, something which had been one of the strongest assets in the performances that the side put in at the end of last season. In some quarters one of the biggest failings of previous regimes was the insistence of using two defensive midfielders, which was considered too defensive and reactionary rather than being pro-active and trying to dominate games, as it were. (holdingmidfield.com)
The enigmatic German hasn't even had a summer transfer window in charge of Liverpool yet but the scars from previous regimes are too ugly to ignore. (anfieldindex.com)