Large STL files

How can I reduce a STL file that is 354mg to 100mg so I can carve in 3D easel? Is there a program easel people use that doesn’t cost an arm and a leg to do this?

This livestream recording shows how I do this using Blender. there are also other softwares that can do this process… MeshLab, I think Windows 3D Builder can also do this task…