Have some questions

Je

So my 7 year old has bery bad body oder under her arms i bought her deoderant and she spread it allnover her door handle and on the stairs so i told her until she can be responsible i wasnt going go buy another one and when she has her bath i would show her how to wash properly. i feel guilty for saying and doing that but she needs to learn to use it properly she has also in the past asked about shaving she has peach fuz under her arms im kind of at a loss here what do you guys think is a good age for her to learn to start shaving