## Reproduction steps Given a multivar setting (i.e. "plugin"): ``` // throws LibGit2Sharp.LibGit2SharpException: 'entry is not unique due to being a multivar' repo.Config.Unset("plugin"); ``` ### Expected behavior Provide an `UnsetAll(key, level)` pair of overloads that basically expose the existing [UnsetMultivar](https://github.com/libgit2/libgit2sharp/blob/master/LibGit2Sharp/Configuration.cs#L256) behavior. ### Actual behavior Exception thrown: `LibGit2Sharp.LibGit2SharpException: 'entry is not unique due to being a multivar'` ### Version of LibGit2Sharp (release number or SHA1) 0.26.1 ### Operating system(s) tested; .NET runtime tested .NET Core 2.1