Hi,
You may consider to use LXDE. Please check
Save 1GB of Memory! Use LXDE on your Jetson - JetsonHacks
For having more freespace, please refer to
DS app running on SD, not running on eMMC - Part II - #5 by DaneLLL
If you don’t need CUDA or TensorRT, you can do only this step:
$ sudo apt remove --purge thunderbird* libreoffice* chromium*