You don’t need to uninstall it.
Create a file (if there is not already one) ~/.config/redshift/redshift.conf and add to it:
[redshift]
location-provider=manual
[manual]
lat=xxxx
lon=yyyy
Put in the relevant values for xxxx and yyyy. If the file is already there, just edit it according to your preferences.
Then start the user service:
systemctl --user enable now redshift.service
Check its status:
systemctl --user status redshift.service
For an example of redshift.conf, see:
https://raw.githubusercontent.com/jonls/redshift/master/redshift.conf.sample