Deinstall Grid Infrstructure Oracle 11g

First Collect all the below information

$GRID_HOME/bin/crsctl stat res -t
$GRID_HOME/bin/crsctl stat res -p
$GRID_HOME/bin/crsctl query css votedisk
$GRID_HOME/bin/ocrcheck
$GRID_HOME/bin/oifcfg getif
$GRID_HOME/bin/srvctl config nodeapps -a
$GRID_HOME/bin/srvctl config scan
$GRID_HOME/bin/srvctl config asm -a
$GRID_HOME/bin/srvctl config listener -l <listener-name> -a
$DB_HOME/bin/srvctl config database -d <dbname> -a
$DB_HOME/bin/srvctl config service -d <dbname> -s <service-name> -v

On all remote nodes, as root execute:
# <$GRID_HOME>/crs/install/rootcrs.pl -deconfig -force -verbose

Once the above command finishes on all remote nodes, on local node, as root execute:
# <$GRID_HOME>/crs/install/rootcrs.pl -deconfig -force -verbose -keepdg -lastnode


As grid user, execute:
$ <$GRID_HOME>/deinstall/deinstall
$ <$GRID_HOME>/deinstall/deinstall