I tried to truncate table and getting this error message

Cannot truncate table 'CoreMessaging_Messages' because it is being referenced by a FOREIGN KEY constraint.

I tried the truncate table CoreMessaging_MessageRecipients alone and getting this error message

Cannot TRUNCATE TABLE 'CoreMessaging_MessageRecipients' because it is being referenced by object 'vw_CoreMessaging_Messages'.

And the DELETE FROM I am getting this error message

Timeout expired. 

Any suggestions how to purge or delete all messages, as I have over 100K 

Thanks in advance.

Many thanks Sebastian for your elaborate reply, I resolved the issue with your advise as per the following :

I tried to drop the FK but faced errors, but when I shrunk the database the script execution went seamless.

There are the steps:

Executed: TurboUnSchema

Then

alter table CoreMessaging_Messages drop FK_CoreMessaging_Messages_CoreMessaging_NotificationTypes

alter table CoreMessaging_MessageRecipients drop FK_CoreMessaging_MessageRecipients_CoreMessaging_Messages

alter table CoreMessaging_MessageAttachments drop FK_CoreMessaging_MessageAttachments_CoreMessaging_Messages

Executed again (to be in the safe side): TurboUnSchema

Then

use [MyDNNDateBase]

truncate table CoreMessaging_Messages
truncate table CoreMessaging_MessageRecipients

truncate table CoreMessaging_MessageAttachments

Finally: TurboDNN734 then TurboSchema734

I have DNN CE 7.3.4 tried to apply DNN Turbo Base Version 0.9.7 (2015-02-12), produced errors. But with DNN Turbo Base Version 0.9.6 (2014-11-17) executed successfully, checked the FK they are back like before :)