Conversion of EASM CAD files to IGES format is not possible. You need the source from which the EASM files was made and then save the assembly file in Solidworks to something useable in other CAD software.
Convert SolidWorks eDrawing assembly data to IGES 3D exchange format.
We found one software available in the database for this conversion.
Microsoft Windows software - convert easm to iges on Windows
A 2D and 3D CAD construction software
Convert from easm file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.