To cleanup the environment, you have to manually stop/unregister all the exctract and delete them. Also, don't forget the trail files as they might be confused.

Furtunetely, there is a quick script for that:

#!/bin/bash
#----------------------------------------------------------------------
# DISCLAIMER:
#    This script is provided for educational purposes only. It is NOT
#       supported by Oracle World Wide Technical Support.
#    The script has been tested and appears to work as intended.
#       You should always run new scripts on a test instance initially.
#
#----------------------------------------------------------------------
# SHELL clean-up.sh
#       Executes the steps necessary to clean up the environment after lab 8
cd /u03/ogg/ogg_src
./ggsci <<EOF
dblogin useridalias ogg_admin 
stop er * !
sh sleep 2
delete er * !
sh sleep 2
delete trandata ogg1.simulapp.*
sh sleep 2
unregister extract ezdta database
sh sleep 2
exit
EOF
cd /u03/ogg/ogg_trg
./ggsci <<EOF
dblogin useridalias ogg_dwnadm 
stop er * !
sh sleep 2
delete er * !
sh sleep 2
delete trandata oggdwn1.simulapp.*
sh sleep 2
UNREGISTER EXTRACT EFBM DATABASE
sh sleep 2
exit
EOF

export ORACLE_SID="CDB12c"
sqlplus sys/oracle as sysdba   <<ENDOFSQL
set echo on
set feedb on
alter session set container = ogg1;
drop user simulapp cascade;
exit
ENDOFSQL
sleep 5
export ORACLE_SID="DWNSTR"
sqlplus sys/oracle as sysdba   <<ENDOFSQL2
set echo on
set feedb on
alter session set container = oggdwn1;
drop user simulapp cascade;
exit
ENDOFSQL2
sleep 5
export ORACLE_SID=""
rm -f /u03/ogg/ogg_src/dirdat/*
rm -f /u03/ogg/ogg_trg/dirdat/*
rm -f /u03/ogg/ogg_src/dirprm/ezdta.prm
rm -f /u03/ogg/ogg_src/dirprm/pzdta.prm
rm -f /u03/ogg/ogg_src/dirprm/rfbm.prm 
rm -f /u03/ogg/ogg_trg/dirprm/efbm.prm
rm -f /u03/ogg/ogg_trg/dirprm/pfbm.prm
rm -f /u03/ogg/ogg_trg/dirprm/rzdta.prm
cd ~
rm -rf dpump

cd /home/oracle/labs/Practice08/configs
echo "Clean-up script completed"

Please replace my variables with your variables. The script is in-progress after all. Will add the feature to automatically detect the directories and the SIDs on later stage.