Address review comments

.circleci/do-rtl-build.sh

@@ -52,10 +52,6 @@ fi
 
 # enter the verilator directory and build the specific config on remote server
 run "export RISCV=\"$TOOLS_DIR\"; \
-     export LD_LIBRARY_PATH=\"$LD_LIB_DIR\"; \
-     export PATH=\"$REMOTE_VERILATOR_DIR/bin:\$PATH\"; \
-     export VERILATOR_ROOT=\"$REMOTE_VERILATOR_DIR\"; \
-     export COURSIER_CACHE=\"$REMOTE_WORK_DIR/.coursier-cache\"; \
      make -C $REMOTE_SIM_DIR clean;"
 
 read -a keys <<< ${grouping[$1]}