To delete all names use the following macro
Sub DeleteNames()
Dim nm As Name

For Each nm In Names
ActiveWorkbook.Names(nm.Name).Delete
Next

End Sub

For the second problem
lower the number of formats use...
Select a range, clear formatting for that range then do it in a minimal way

"WINS" wrote:

1. I have been passed a workbook which contains named ranges which are no
longer relevant or whose relative cells no longer exist, more than one
hundred of them.

I want to know how can I get rid of all of them easily rather than deleting
one by one and have error messages or names simply wont delete?

2. The same workbook sometimes does not allow me to insert rows or colums
and displays the message 'too many cells formats'

Can anyone help me overcome these problems.

Thanks for your usual help.