Rename Tabs and Labels in Salesforce Setup can be used to rename related list. Check the following steps for reference.
1. If the child object is a custom object: From Setup, go to Create > Objects > (Name of Object).
If the child object is a standard object: From Setup, go to Customize > (Name of Object) > fields.
2. Locate the custom lookup or master-detail field referencing the parent object.
3. Click the “Edit” link next to the relationship field.
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4. Rename the “Related List Label”.
5. Remember to “Save” when finished.
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