Welcome to PayPal Community Forum and Thank you for the post! I am sorry to know that you're unable to edit the phone number. Kindly note you can only remove a phone number if you’ve at least two added to your PayPal account. To edit your phone number, please take a look at this help center article. If the issue still persists, you can certainly reach out to our customer support team through the available contact options on our website so that our advisors can help you accordingly.
I hope this helps,
If this post or any other was helpful, please enrich the community by giving kudos or accepting it as a solution.