From July 2015, Google Adwords will permanently delete any removed campaigns, adgroups, keywords and adverts from your Google Adwords account.
Google will be removing anything within your Adwords account which have either:
1) never occurred impressions, or 2) been removed from your account for more than 100 days.
Google have reported that your unwanted content in Adwords sits in the background and clogs up and slows the processing load. To un-cluster your Adwords account, Google will be making the removal part of an Adwords account permanent. This will mean that you cannot re-enable any removed content in your Google Adwords account or look at the statistics of previously active campaigns.
If you want to keep any removed campaigns, adgroups, keywords and adverts you should change the status from removed to paused. You will still be able to re-activate and analyse any paused data.