It seems you have another roots.m file which is different from MATLAB's built-in roots function.
Please check the following command
You will get custom roots.m (in bold) and built-in roots.m files.
<MATLAB_ROOT>\toolbox\parallel\gpu\@gpuArray\roots.m % gpuArray method
<MATLAB_ROOT>\toolbox\matlab\polyfun\roots.m % Shadowed
Rename the custom roots.m file to such as myRoots.m.