ANSWER- There are a few things I can suggest but the first is to have a full on frank conversation about what it is that you do in an attempt to put her mind at rest. It is sad that our press as witches seems to still be more associated with Satanism than the genuine practise of the craft but this won’t change unless people are prepared to stand up and be honest and transparent about what being a witch really involves.
That said I think sometimes using the word “witch” can raise hackles among those with predefined notions of witches. Rather than announcing what you are, I’d suggest you go along the lines of more what it is you do. It’s a good opportunity to think about what being a witch means to you as an individual and then working out how you can express this in language that your aunt will understand and relate to. In my opinion you’d get a lot further with “I like to work closely with nature,” or “I see my path as Earth centric rather than deity focused” than you will with “I’m a witch.”
(Incidentally this is no criticism of Satanism. I’m sure reputable Satanists are just as annoyed at the incorrect perception of the cross over between Satanism/Witchcraft.).
I’d also suggest that you ask your aunt to treat you with the courtesy any human being deserves. Tell her that if she wants to discuss one of your possessions with you then you are willing and open to that discussion but you do not believe it appropriate she bin things you own without consent. But be prepared to compromise. It is your aunt’s house and she has the right to make the rules relating to what happens in her house. She does not however have the right to dictate the path you follow. If the two of you cannot find a harmony then I think you need to find a way to practise your craft in an environment that isn’t her home. (I remember one young witch finding a compromise where she borrowed a friend’s garage for ritual. Possibly something like that might work for you.)
From a magical perspective there are a couple of spells that would work in this situation. You need to be clear about what you want to achieve. Do you want to focus on hiding yourself or on influencing your aunt either to not see or not react to what it is you want to do.
If the former I would suggest a shielding spell. Something simple such as wrapping up a depiction of yourself practising the craft (say a picture or an item that symbolises to you your path as a witch) in some tin foil and visualising your aunt’s prejudices and preconceptions bouncing back off you whenever she tries to interfere with your work. You could adapt this slightly by using dark cloth or black paper to hide your work from your aunt. The success of this spell would be getting the visualisation strong enough relating to your aunt’s mind being wiped of all curiosity relating to your craft.
If you’d rather work directly against your aunt then I think a binding spell focused on binding her influence over your path is probably the way to go. You could get a bit more creative and look to influence her core belief but that might be a bit ambitious at this stage. I’ll include a link on binding spells below. Think about adapting the basic idea so she is powerless to act upon her dislike of your chosen path.
But in all honesty good old upfront conversation is the best place to start. Find some good articles about witchcraft that may help explain the basics and reinforce to your aunt that you are not some blood sacrificing creature of the night (lol). People tend to be more amenable to any point of view when they have the education and knowledge that takes away the fear and when it comes to portraying modern witchcraft in a positive light I think you will find most of the internet is on your side!