Fetching details from the dictionary...

to finish; to get it over with; to conclude
to settle; to pay back
to get along (without something); to make do with (without)
手続きを済ませるのに一時間かかった。
It took an hour to complete the procedures.
朝食はコーヒーだけで済ますことが多い。
I often get by with just coffee for breakfast.
用事を済ませてから合流することにした。
I decided to join after finishing my errands.