"To hide the evidence" means to keep something from being seen or discovered, especially when it could be proof of something bad or incriminating. Full definition
In this pup's case, it's all about hiding the evidence of his theft — in his mouth. (wideopenpets.com)
First, firms need to realize that removing a Web page won't hide evidence in our «cache and carry» world. (legalblogwatch.typepad.com)
The prosecution gets no surprise witnesses, no newly found evidence, and can not hide evidence that would work against their case. (law.stackexchange.com)