Idiom relax your grip/hold (definition of relax from the cambridge advanced learner's dictionary & thesaurus © cambridge university press)
To become or to cause (something) to become less tense, tight, or stiff sometimes used figuratively;
To stop feeling nervous or worried
When you relax, you make yourself calmer and less worried or tense.
Meditation relax music channel presents a relaxing stress relief music video with beautiful nature and calm music for meditation, deep sleep, music therapy.
The meaning of relax is to make less tense or rigid :
How to use relax in a sentence.