I forget where I saw this but it's an amazing tip since managing mods drove me crazy until I saw it. I'm sure it's been covered before but posting again with the new DLC drop and everyone no doubt needing to be able to adjust their current mods. This tip also works with all other categories of workshop items, as I also go over as well.

The first step is to get the URL to your subscribed items

1. Go to Steamcommunity.com from inside your web browser of choice. This will not work in the Steam client. You must use a web browser for this exercise.

2. Then go to your subscribed items by visiting the CS:Workshop ( https://steamhost.cn/steamcommunity_com/app/255710/workshop/ ), click on the Browse menu at the bottom of the Cities:Skylines graphical header near the top of the workshop page, then select Subscribed items from the pull down menu (circled in red below).

3. Once you are in your subscribed items, the url in the browser should end in &browsefilter=mysubscriptions

To filter your subscribed items: add the tag for what you want to filter by pasting the below to the end of the URL with no spaces:

&requiredtags[0]=Tag

Substitute the word Tag for what you want to filter. Some examples:

For Mods: &requiredtags[0]=mod
For Props: &requiredtags[0]=prop
For Trees: &requiredtags[0]=tree
For Map Themes: &requiredtags[0]=map+theme

My URL to show only the mods I am subscribed to looks like:

https://steamhost.cn/steamcommunity_com/id/docno42/myworkshopfiles/?appid=255710&browsefilter=mysubscriptions&requiredtags[0]=mod

Obviously, you should see your Steam username where docno42 appears in the URL above - after all that's *my* URL I included just for an example.

If you are successful you will see the tag reflected in your asset list view - here you can see I am filtering on Mods with the green Mod tag showing in the lower left in this screen shot:

• Note that tags with a space like Map Theme need to use a + instead of the space in the URL you construct. The URL should have NO SPACES in it.
  
  For Map Themes: &requiredtags[0]=map+theme
  
  Note the space is replaced with a + sign.
  
  
• Once you get your URL working, bookmark it for easy access!
  
  
• Remember: to the left of the & in the examples is the rest of a long URL that's specific to you. Your just adding the &requiredtags[0]=Tag to the end of the URL that's already there, with no spaces anywhere in the URL! The URL will not work if you have spaces; if it doesn't work that's the first thing to check and correct.
  
  
• Anything that is in the menu down the right side (the two sections Browse By Tag or Assets) in the top level Workshop view from step 2 are fair game for this tip. Below is the list at the time I wrote this guide - items can be added/changed/deleted so always check the workshop to see what the current tags are; I present this list to provide an idea of what's available. Remember for any tag with spaces to substitute the + sign for the spaces as you build your custom URL!
  
  Map
  Mod
  SaveGame
  District Style
  Map Theme
  Scenario
  Building
  Prop
  Tree
  Vehicle
  Intersection
  Park
  Electricity
  Water & Sewage
  Garbage
  Healthcare
  Deathcare
  Fire Department
  Police Department
  Education
  Transport
  Transport Bus
  Transport Metro
  Transport Train
  Transport Ship
  Transport Plane
  Unique Building
  Monument
  Residential
  Residential Low
  Residential High
  Commercial
  Commercial Low
  Commercial High
  Commercial Tourism
  Commercial Leisure
  Industrial
  Industrial Generic
  Industrial Farming
  Industrial Ore
  Industrial Oil
  Industrial Forestry
  Office
  Transport Taxi
  Transport Tram
  Transport Monorail
  Transport Cable Car
  Citizen
  Road
  Park Area
  Industry Area
  Industry Area Farming
  Industry Area Forestry
  Industry Area Oil
  Industry Area Ore
  Unique Factory
  Campus
  Campus Area
  Campus Trade School
  Campus Liberal Arts College
  Campus University
  Varsity Sports
  Color Correction LUT
  Cinematic Cameras