Fig.: to take an irreversible course of action, without possibility of backing down

He made mistakes when he was young, but then he burned his bridges behind him and started a new honest life

Ha sbagliato in gioventù, ma ha tagliato tutti i ponti con il passato e si è rifatto una vita onesta

Hillary said she saw little harm in maintaining cordial relations with her former husband Thomas now that she no longer lived with him and no longer felt threatened by him. She did not feel that it was necessary to cut off all ties or to burn all bridges or to treat him in a hostile manner

Ilaria ha detto che non vedeva nessun pericolo nel mantenere rapporti cordiali con il suo ex Tommaso, ora che non viveva più con lui e non si sentiva più minacciata da lui. Non le sembrava necessario, poi, spezzare ogni legame o tagliare i ponti o trattarlo in modo ostile

He's quitting his job to go and work for a competitor. I hope he realizes that he's burning the bridges behind him

Ha dato le dimissioni per andare a lavorare da un concorrente. Spero che si renda conto che vuol dire tagliare i ponti dietro di sé

The expression comes from the military action of burning the bridges crossed by the army (or the boats used to cross a river) to cut off the possibility of retreat or to delay the enemy. Another explanation is that borders are often defined by rivers and, especially in the past, cutting the bridges was the first signal that a war was about to break out