You can download here
./scripts/build.sh sunxi_Lamobo_R1
cd openwrt
make menuconfig
make defconfig
make V=s
gzip -k -d openwrt/bin/sunxi/openwrt-sunxi-Lamobo_R1-sdcard-vfat-ext4.img.gz
dd if=openwrt/bin/sunxi/openwrt-sunxi-Lamobo_R1-sdcard-vfat-ext4.img of=/dev/YOURSDCARD
make clean
deletes contents of the directories /bin and /build_dir. make clean does not remove the toolchain, it also avoids cleaning architectures/targets other than the one you have selected in your .config
make dirclean
deletes contents of the directories /bin and /build_dir and additionally /staging_dir and /toolchain (=the cross-compile tools) and /logs. 'Dirclean' is your basic "Full clean" operation.
make distclean
nukes everything you have compiled or configured and also deletes all downloaded feeds contents and package sources.
CAUTION : In addition to all else, this will erase your build configuration (<buildroot_dir>/.config), your toolchain and all other sources. Use with care!