Restraining her sounds a bit dramatic, I think it would be even more frustrating for her if she cannot/is not allowed to express her feelings/frustration, especially at such a young age.
(or does she really hit her head against the wall on purpose or pull out hair or anything like that? if that's the case I would advice to talk to someone about it)

She won't hate you for saying no, they seek out and test limits, because they need limits.
It gives stability to know what you can and cannot do.
It sounds to me that you're doing alright with saying no and taking the things away. Just be consequent. no means no, tantrums won't effect your decision.