Richard nixon left the white house because he was

Resigned, otherwise would have been impeached.  

Explanation:

After the watergate scandal , Richard Nixon lost most, if not all, of his political support. In the face of certain impeachment, he resigned on the 9th of August, 1974. He was issued controversial pardon by his successor, Gerald Ford.

What was watergate?

The watergate scandal was a scandal that occurred during and after the 1972 presidential election. A janitor had discovered clues/hints that 5 former FBI and CIA agents had been listening into phone calls and secret papers were stolen from the Democratic Party, and Nixon's competitor, George McGovern. The scandal was then traced back to Nixon himself.