Dear Pavan,
seeing the screen shot,it is confirmed that it is a first level WBS element
In your project while budgeting only enter the WBS element for which you require budgeting.
in the other words,carry out budgeting process for all 1st level WBS elements independently so as no budgeting or AVAC status is activated for the WBS element ,you can create PR-PO without budgeting that 1st level WBS element.or wbs under it
In future if you require to do budgeting and AVAC,based upon the assigned and the future requirement you can carry out budgeting for that 1st level WBS element. in this case you need not go for the changes in the customization .
hope this shall help you