Enrico,
For each new release of ArchiCAD I recreate my office template from scratch so that I am not bringing in any unnecessary legacy data, the template for my office is approx 2Mb in size.
The process I follow is:
1- start new project using default template
2- delete all content & stories
3- delete all sections, elevations, interior elevations, worksheets, details, 3d documents, schedules, indexes, lists, info, sheets and sheet masters from navigation palette
4- delete all layers, layer states, pens, line types, fills, composites, profiles, materials, zones, cities, operation profiles using attribute manager
5- delete all loaded libraries and embedded library parts
You will now have a file that is as empty as you can as there are some linetypes, fills, sheet masters, sheets etc that cannot be deleted.
Save the file and now you can start rebuilding the template.
I would suggest creating a base template and a full template, the base template would contain only the attributes needed for all of your projects and would be the base from which you start new projects, the full template would contain all attributes that may be used. You can use the attribute manager to quickly import attributes from full template into your project as the need arises.
To rebuild the template it is essentially the reverse of the process used earlier:
1- import layers, layer states, pens, linetypes, fills, composites, profiles, materials, zones, cities operation profiles etc from your current template using the attribute manager.
2- load minimum libraries and embed any required library parts
3- import required schedules, lists, indexes, sheet masters
Best of luck,
