This article provides the configuration equivalent for Cisco's "no ip source-route" in Juniper.

It is disabled by default in Juniper and if you want to enable it you can config below:

# set routing-options source-routing ip disable

Please refer to below document for more information :

https://www.juniper.net/documentation/us/en/software/junos/cli-reference/topics/ref/statement/source-routing-edit-routing-options.html