Immediatelly after installing 10.13 Beta (17A264c) whatever I deleted from boot disk (converted to APFS), it never freed any space. I deleted some 25 GB and still got warnings that I cannot decompress XCode 9 installer. Did the same on SD card (delete some 20 GB, copied the xip there, decompressed, no problem. Looks like deleting data on HFSX works fine, but not on the boot disk in APFS.
Unfortunatelly additions of data (like the Xcode) still register, so I am quickly running out of disk space.