You are right, the dynamic change of grid columns is not supported at present. The Beta of Q2 release is scheduled for this week and you should be able to download and test it very soon. Unfortunately the functionality that you are looking for is not planned for this release, but if you are interested in what is coming next you may take a look at the official roadmap
Regarding to your second question, the grid currently does not expose destroy methods, however the implementation of such functionality has been discussed and we will consider its implementation for one of our future releases. Actually this idea
has been already submitted at KendoUI user voice forum, so if you wish you may cast a vote for it or leave a comment. The more votes it collect, the higher priority it will have.
the Telerik team
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