Memory leak in WPF graph (VectorRenderTarger )

I check memory leak on the WPF graph.

I see that there is a variable that called: VectorRenderTarger, and it never erased from the memory.

The amount is always changing depending on the number of existing plots on the screen (in the attached project is six plots every time).

When I clear the data & add new data - new (6) VectorRenderTarger variables are added, and the old (6) not erased from the memory.

Is there a way to make this variable to be removed from memory?