Removing columns in Power BI source file

Lets say I have an excel table with 100 columns and I load this into Power BI, however I only want to use 30 columns.

As the 100 column file is how the data is downloaded from our system I do not want to delete any unwanted columns here, this I will do in Query as the future files will include these columns.

After the file is loaded into query, I transform the data and remove the unwanted columns.

Now I discover the future downloaded files (source data) exclude the unwanted columns however it clearly doesn't match what was originally loaded into Power BI. 100 vs 30 columns.

How can I change the way Power BI/Power Query views the file as I want to now upload the new file now containing only 30 columns, not 100.

I have looked in Advanced Editor and I didn't actually remove the umwanted columns I selected the required ones and used Remove Other Columns

Thanks

Paul