FWIW, these files are generated by a program using the SQLite database engine. The etilqsin etilqs_aXfJzgEx2fKH3rg is lower case SQLite spelled backwards. The rest of the filename are simply randomly selected letters and numbers that attempt to create a unique file name that will not conflict with any previously named file on your system.
It would appear that one or more programs on your system is using a form of SQLite to store data. Your problem with not being able to delete them is likely due to them being active in the parent program. If you reboot your computer you should release them and be able to delete them. Unfortunately, you will probably generate a new set of etilqs_XXXXX files.