I temporarily need space on my iphone without deleting my library

[carmid]

Hi,

I have an iphone 5 and want to upgrade on IOS 8. However, this temporarily requires 5 GB of free space that I don't have right now.

Therefore, I would like to delete the Spotify music that I made available for offline utilization. BUT: I would like to keep library, i.e. the names of all the songs, interprets etc. - only the underlying data shall be deleted so that it opens up memory space for the upgrade on IOS 8.

Do you guys have an idea?

Thanks

Carsten