problem with add/remove section

[=?Utf-8?B?eWluZ3lhbmc=?=]

I noticed the other day that the change/remove option was no longer available
in all the program listed in the add/remove section. Likewise, I have to
reinstall the programs to get that option. however, some programs need to be
uninstalled first and I cannot do that without the change/remove options.
what should i do? i need to remove some updates to completely install the
program