"I am not wearing shoes."
Translation:Saya tidak memakai sepatu.
My Malay friends have said that sepatu is always implied as a pair of shoes, so plural doesn't really make sense, unless talking about many pairs of shoes, so in this context it is just sepatu.
The rough translation of 'saya bukan memakai sepatu' is "It isn't shoes I am wearing" where as 'saya tidak memakai sepatu' is "I'm not wearing shoes" so the second is more accurate.
There is a good article about negations that you can find on the lenguage materials, making the story short, "Tidak" is used to deny verbs, and "bukan" is used to deny nouns... So in this case you want to say "no" to the verb, if you would like to say that you are wearing something in your feet that is not shoes, then you would use "bukan"