Impeachment is not the same as being removed from office. It is the first step to the process however. Impeachment is the bringing of charges against an official in office. Once charges are brought, a trial must be held on the Senate with the Chief Supreme Court Justice presiding. If the trial ends in a conviction, the result is removal from office. However, the Chief Justice for nearly the past 20 years is a staunchly conservative man appointed by the 2nd bush administration in 2005.
Impeachment was never really a threat to Trump while in office. Just a way for Congress to tell the president that they know the bad shit he's doing and they don't like it. As long as the supreme court remains absolutely stacked with conservative appointees, there will never be a removal of office of a favored Republican president.