You should keep them. They are in your Library folder and everyone has them. There is no official meaning of the "AlchemistGenerationTask" files, just as with most System Files you will see on your computer. Since they are in a folder called PhotoAnalysis, that at least gives you a clue it is related to photos and it is also in a tmp folder so the contents will change frequently. They take up very little storage space, so removing them would not be a beneficial.
The s7_30.png file is in the News folder of your Library, so I would take the same approach there. This file is only 8Kb. You are not going to have any impact on your storage by deleting these minuscule files and the risk is that you are going to cripple your user folder and going to start seeing problems.
For regaining storage space, stick to these folders:
- Application
- Documents
- Downloads
- Desktop
The one location in the Library folder where I could see deleting any files is the Application Support folder, and would only recommend to delete folders there that specify a third party app that you no longer use. If you are unsure of a file, then do not delete it.
Stay away from any Cleaner apps such as CleanMyMac as those will cause you problems. There are other programs that simply identify the largest files on your computer, but for one you can do that simply by sorting Finder by size and two, you still need to be very careful about deleting any System or Library file.
Make sure you have a valid backup before you venture into any of these deletions as you may end up with a complete loss of data if your computer is unable to boot or you are no longer able to log in to your user folder.
