to burn one's bridges

[Theseus]

Last one!!
To burn one's bridges (behind one)
1. Lit. to cut off the way back to where you came from, making it impossible to retreat.
--The army, which had burned its bridges behind it, couldn't go back.
--By blowing up the road, the spies had burned their bridges behind them.
2. Fig. to act unpleasantly in a situation that you are leaving, ensuring that you'll never be welcome to return.
--If you get mad and quit your job, you'll be burning your bridges behind you.
--No sense in burning your bridges. Be polite and leave quietly.
3. Fig. to make decisions that cannot be changed in the future.
--If you drop out of school now, you'll be burning your bridges behind you. You're too young to burn your bridges that way.

 

[sarant]

We do say κόβω τις γέφυρες.
Note also "τα καράβια μου καίω", but this is a good song rather than an idiom.

 

[azimuthios]

Κόβω κάθε επαφή ή κόβω τον ομφάλιο λώρο, αλλά σε άλλη περίπτωση.

Also, ρίχνω μαύρη πέτρα πίσω μου when you take a conscious decision never to come back to the place you used to live or work in.

 

[cougr]

Also, κλείνω πόρτες .

 

[crystal]

And "κόβω κάθε δεσμό".