How can I customize the report to include/exclude certain fields and export in excel?

Please follow the below steps for standard customization in report:
 if you want to remove any column from a report:
 1: Open report in which you want to add / remove some column
 2: Click on cutom column which is available in report on top right 
 3: Enter format you can specify format like New etc
 4: Then untick field ID of available column and click on same format 
 5: when you open same report then you will get select format option then you have to select your format which create through custom column 
 or 
 If you want to add new column in a report then:
 1: Open report in which you want to add / remove some column
 2: Click on cutom column which is available in report on top right 
 3: Enter format you can specify format name like New / format A etc
 4: Click on add new column 
 5: Specify the column heading which column you want to add
 6: Specify the position after which column you want to add new column
 7: Select the data type, your column data type is text, date, numeric, yes/no etc
 8: Specify Alignment your column data left /right and specify the no. of character for column data
 9: Select data field and select category from which category related details you want to new column 
 10: If you select Item master/account master then you have specify currentely item / account details showing with which field id in default report and specify on master name column 
 11: Click on field & select field 
 12: save field and save format 
 13: reopen report with new format which you create through custom column