unclenching

/AH0 N K L AH0 N CH IH0 NG/
verb
  1. 1

    To open (something that was clenched).

    โ€œThe baby stopped crying and unclenched her fists.โ€

  2. 2

    To relax, especially one's muscles.

    โ€œBill, take some deep breaths and unclench.โ€

Source: https://en.wiktionary.org/wiki/unclench, https://en.wiktionary.org/wiki/unclenching