Deleting container contents

This is probably a very basic, simple task but I have a couple of questions regarding container fields. I currently have a container field in FMP13 that is used to store a PDF document. The field has been optimized to support PDF information.

The 1st time I enter a table record and insert a PDF into my container field I can either 'right click' and insert or use the menu bar and 'insert'. If I want to replace the PDF, the only way I can accomplish this is to use the menu bar. I'd like to be able to 'right click' whenever I want to insert a PDF. Is the menu bar my only option for updating my container information?

I find no way to 'delete' the contents of my container field. I know I've got to be overlooking an obvious solution, but I sure don't see any way to accomplish this.

I've tried setting the container field to be both stored locally as well as externally, always with the same results.

Occasionally, when I try to replace a PDF the FileMaker Pgm will abort. When I restart the program it will insert the PDF just fine. At this point in time I'm not sure if it's a FileMaker issue or an issue with my server. If you have any suggestions on how to approach resolving this dilemma I'd appreciate it.