cast loose
To unfasten; untie; let loose (as a rope holding a boat).
The captain of the boat cast off the line and we were soon out in open water.

1b. To untie a rope holding a boat or something suggesting a boat.
We cast off and set sail at 6 A.M.

2. To knit the last row of stitches.
When she had knitted the twentieth row of stitches she cast off.

3. To say that you do not know (someone) any more; not accept as a relative or friend.
Mr. Jones cast off his daughter when she married against his wishes.

[TahlilGaran] English Idioms Dictionary ▲