Let's be pragmatic here. She didn't decide the logistics of her email server and how to secure it or delete emails. Her IT intern did this.
Let's be realistic here. She didn't tell her IT guy what tools to use. She didn't have to. Someone -- and it doesn't take too much intelligence to guess who -- gave a directive to make that server and all its contents disappear Jimmy Hoffa style. That directive was given only after the existence of the server became public knowledge and its contents were requested. Can guilt be proven by such an action? No. But can anyone make any remotely plausible, intelligent, cohesive argument as to why someone running for POTUS would knowingly put themselves in such an awkward, damaging position?
Clinton is no fool. She knew wiping the server after it was discovered would leave her open to charges of hiding things. The most plausible explanation of why she'd do this was because there were things on the server that were even more awkward and damaging.