Hey

Looks like you're trying to do this in your Production Org (assuming you have sufficient privielges to author / edit code)

If so, you can't edit / delete code in Production. It has to be deployed via Change Sets or the Force.com IDE (Or the Migration Tool)

If this is a Sandbox, then your User is prolly missing sufficient rights to do this sorta thing.

Hello,

I have enabled development mode. I think this is production org ( How do I confirm ) . I have sufficient privilege as I have logged in as a System Admin.

So according to your suggestion, I can sync up my this organization with my eclipse and then make a change in eclipse organization and again deploy back to production organization..

Is that what you suggested ?

Thanks

Raj

If you logged in via https://login.salesforce.com then its Prod 

If via https://test.salesforce.com then its a Sandbox (sanboxes tend to be named like naX, csX or tappX) Also it should say Force.com Sandbox in the top right or top centre (depending on your UI theme) in case of a Sandbox.

So if you are logged in to Production, then yes, you'd have to deploy a deletion from one of the sandboxes.

Thanks I have one very related query,

I am trying to delete one of custom tag which refers to Visual Force Page. Now If I try to delete tab it complains that Visual Force page references it so It can't delete and If I try to delete VF page first, it complains that one Tab has reference to it so It can't delete.

This seems to be cyclical dependency and idea how to delete both tab and VF page ?

Thanks