How to resize table and remove outer table within a table from MS Word?

I hear ya - tables can be time consuming beasts

Looking at your file - I'd stip the outer table.

Insert a text frame and add a border as an object style

Then add your table to the text frame which is anchored

In the attached file I've setup an object style (Window>Sytles>Object Styles)

You can copy the same text frame and then paste your new table (without the outer table into it)

Then for the width of the table - you can select across the rows and then fit the table within the text frame.

It's not easy working with tables and I admit it's time consuming.

I hope you do find a script. 

But if you master

Anchored Objects

Object Styles

Table Styles/Cell Styles

Plenty of tuts online. 

Set 1 up perfectly - and the rest and can be done by applying the Style

And then if something needs to change you can alter the style and it will chnage globally.

It's so important to get the 1st one right and setup with all the necessary styles in place.

There's no reason why you can't keep the outer table that it's nested into - but using styles might mess up the other table/cell styles - dunno never tried it but off top of my head it would be a bit messy.

Take your time with the 1st table and work it correctly and the rest should flow a lot easier.