Injuring One's Body and Annulment of Vows

Hello. I have some important questions: 1. When I am under stress I like to peel the skin on my lips and sometimes it bleeds. Is this permitted, or is it considered injuring one's body? And if there are half‑detached pieces of skin, is it permitted to pull them off? 2. In the past I said that I do not want to dress my children in red shirts and I specified that this was without a vow (bli neder). May I now reconsider this acceptance?

Shalom and blessings 

1. This is not prohibited. 

2. It is permitted. 

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