Unite Tool
Ribbon menu → Bodies tab → Booleans container → Unite Tool 
or
(Classic) Build → Bodies/Geometry → Unite Tool
Creates complex geometry by joining two intersecting solids. It merges the second part you select into the first part, resulting in a single part.
The union has a mass computed from the volume of the new solid. Any overlapping volume is only counted once.
Learn about Creating One Part from the Union of Two Solids