You can't unring a bell sentence informal
Once something has been done, you can do nothing but face the consequences.
Do not do anything without thinking carefully because you can't unring a bell.
You must have known you would be punished for what you did. You can't unring a bell.
The idiom has been in use for the first time in the Oregon Supreme Court case of State v. Rader, argued on May 9, 1912. decided on May 28, 1912. Since then, the idiom is sometimes used in jury trials.